Step-by-step explanation:
S.i =principal x rate x time/100
7,50000x4x4.5/100
13500000/100
135000
A county real estate appraiser wants to develop a statistical model to predict the appraised value of houses in a section of the county called East Meadow. One of the many variables thought to be an important predictor of appraised value is the total number of rooms in the house. Consequently the appraiser decided to fit the simple linear regression model, ^y=β0+β1x , where y= the appraised value of the house (in thousands of dollars) and x= the number of rooms. Using data collected for a sample of n = 74 houses in East Meadow, the following results were obtained:
Answer:
Step-by-step explanation:
Hello!
The statistical model predicts the appraised value of houses in a section of the county East Meadow (Y) in relationship with the number of rooms of the house (X)
For a sample of n=64 houses the simple linear regression was estimated:
^Y= 74.80 + 24.93X
Range of X: 5 - 11
Range of Y: 160 - 300 ($ thousands of dollars)
Interpretation of the estimates of the y-intercept and the slope
y-intercept:
74.80 thousand dollars is the estimated average value of a house in a section of the county East Meadow when the house has zero rooms.
Slope:
24.93 [tex]\frac{thousand dollars}{rooms}[/tex] is the modification of the estimated average value of a house in a section of the county East Meadow when the number of rooms increases on one.
I hope this helps!
Running times for 400 meters are Normally distributed for young men between 18 and 30 years of age with a mean of 93 seconds and a standard deviation of 16 seconds. How fast does a man have to run to be in the top 1% of runners?
Answer:
To be in the top 1% of the runners, the man has to run the 400 meters in at most 55.768 seconds.
Step-by-step explanation:
When the distribution is normal, we use the z-score formula.
In a set with mean [tex]\mu[/tex] and standard deviation [tex]\sigma[/tex], the zscore of a measure X is given by:
[tex]Z = \frac{X - \mu}{\sigma}[/tex]
The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the pvalue, we get the probability that the value of the measure is greater than X.
In this question, we have that:
[tex]\mu = 93, \sigma = 16[/tex]
How fast does a man have to run to be in the top 1% of runners?
The lower the time, the faster they are. So the man has to be at most in the 1st percentile, which is X when Z has a pvalue of 0.01. So he has to run in at most X seconds, and X is found when Z = -2.327. Then
[tex]Z = \frac{X - \mu}{\sigma}[/tex]
[tex]-2.327 = \frac{X - 93}{16}[/tex]
[tex]X - 93 = -2.327*16[/tex]
[tex]X = 55.768[/tex]
To be in the top 1% of the runners, the man has to run the 400 meters in at most 55.768 seconds.
What is the final step in solving the inequality –2(5 – 4x) < 6x – 4?
Answer:
work is shown and pictured
Answer: x<3
Step-by-step explanation:
John has grades of 82 and 98 on his first two history tests. What must he score on his third test so that his average is at least 88?
John's average on all three tests, assuming a score of S on the third test, would be
(82 + 98 + S)/3
He wants the average to be at least 88, so solve the inequality:
(82 + 98 + S)/3 ≥ 88
82 + 98 + S ≥ 264
180 + S ≥ 264
S ≥ 84
So John needs to obtain a grade of at least 84 on the third test to get the average he wants.
The score on his third test is 84 so that his average is at least 88 given first two grades 82 and 98. This can be obtained by using the formula to find average.
What is the formula to find average?Average of observations is the ratio of sum of observations to total number of observations.
How do we find the third grade using average formula?
Grade of first test=82
Grade of second test = 98
let grade of third test be x
Average of the grades = [tex]\frac{82+98+x}{3}[/tex] ≥ 88
[tex]\frac{180+x}{3}[/tex] ≥ 88 ⇒ x ≥ 246-180 ⇒ x ≥ 84
Hence we can say that the score on his third test is 84 so that his average is at least 88 given first two grades 82 and 98.
Learn more about averages here:
brainly.com/question/19004665
#SPJ2
Given f(x) and g(x) = k⋅f(x), use the graph to determine the value of k. Two lines labeled f(x) and g(x). Line f(x) passes through points (-4, 0) and (-3, 1). Line g(x) passes through points (-4, 0) and (-3, -3).
A.) 3
B.) 1/3
C.) -1/3
D.) −3
Answer:
Option D.
Step-by-step explanation:
If a line passing through two points, then the equation of line is
[tex](y-y_1)=\dfrac{y_2-y_1}{x_2-x_1}(x-x_1)[/tex]
It is given that Line f(x) passes through points (-4, 0) and (-3, 1). So, equation of line f(x) is
[tex](y-0)=\dfrac{1-0}{-3-(-4)}(x-(-4))[/tex]
[tex]y=1(x+4)[/tex]
So, function f(x) is
[tex]f(x)=(x+4)[/tex] ...(1)
Line g(x) passes through points (-4, 0) and (-3, -3). So, equation of line f(x) is
[tex](y-0)=\dfrac{-3-0}{-3-(-4)}(x-(-4))[/tex]
[tex]y=-3(x+4)[/tex]
So, function g(x) is
[tex]g(x)=-3(x+4)[/tex] ...(2)
Using (1) and (2), we get
[tex]g(x)=-3f(x)[/tex] ...(3)
It is given that
[tex]g(x)=kf(x)[/tex] ...(4)
On comparing (3) and (4), we get
[tex]k=-3[/tex]
Therefore, the correct option is D.
The equation h = 7m + 8 models the growth of a plant after it was put into a flowerbed. If
m is the number of months since it was planted and h is the plant's height in
centimeters, which statement is valid?
The vertical axis on a graph would
represent the number of months the plant
has been in the flowerbed.
The height of the plant is the dependent
variable.
The domain of the function represents the
height of the plant.
The variable m could be represented as
f(h).
Answer:
2
Step-by-step explanation:
the vertical axis would be h, the plant's height, and the horizontal axis would be m, the number of months. This would make statement 2 the only valid statement.
statement 1: Incorrect, as the vertical axis is the height
statement 2: correct, as h depends on m
statement 3: incorrect, as the domain is the horizontal and represents the number of months
statement 4: incorrect, as h = f(m)
In two sample surveys 125 people were asked about their favorite fruit in the survey 40 people chose apples 64 choose oranges and 21 chose bananas in the second 34 chose apples 63 chose oranges 19 Joe’s banana marine inferred before is this a French trooper by us on the data explain
Answer:
Marianne made an inference that is true based on the data. More than half of the people surveyed in each sample chose oranges as their favorite fruit. Since most people in each sample chose oranges, it is likely that oranges are the favorite fruit of the entire population.
hope it help please mark me as brainliest
The function h(t) = -4.92f^2 + 17.69f + 575 is used to model the height of an object being tossed from a tall building, where h(t) is the height in meters and t is the time in seconds. What are the domain and range?
Answer:
rounded to 3 decimal places ...
domain: [0, 12.757]range: [0, 590.901]Step-by-step explanation:
The function can be put into vertex form:
h(t) = -4.92(t -(1769/984))^2 +575 +4.92(1769/984)^2
h(t) ≈ -4.92(t -1.79776)^2 +590.90122
The value of h(t) is zero for ...
t = √(590.90122/4.92) +1.79776 ≈ 12.75686
For practical purposes, the domain of the function is those values of t between the time the object is tossed and the time it hits the ground. That is, the domain is ...
0 ≤ t ≤ 12.75686
The range is the set of useful vertical heights, so extends from 0 to the maximum height, given by the vertex.
The range is 0 ≤ h(t) ≤ 590.90122.
_____
Alternate interpretation of the question
The function h(t) is defined for all values of t, so that could be considered the domain.
The function h(t) only gives values less than its vertex value, so the range could be considered to extend from negative infinity to that maximum.
What is the value of expression below? 7/2-4.5x3+8
Answer:-2
Step-by-step explanation:
Ok so I’m assuming the x stands for the multiplication sign
7/2-4.5*3+8
Use pemdas
Multiplication first
7/2-4.5*3+8
-4.5*3
7/2-13.5+8
Then addition
-13.5+8
Lastly subtraction
7/2-5
-2
simplify 2(f^4)^2/8f^12
Answer:
Step-by-step explanation:
2(f^4)^2/8(f^12)
2/8= 1/4
f^16/f^12
f^(16-12)= f^4
f^4/4 is the solution
5×100+4×10+6×1+2×(110)+8×(11000)
What is the number written in standard form?
Answer: 8.059
Explanation: It's the digit times the column heading.
are all the rectangles faces the same size
Answer:
A rectangle is a 2 dimensional figure, it is in a plane, so it has two faces, and yes, they are equals.
In each of the following situations, data are obtained by conducting a research study. Classify each Experimental or Correlational.
Research Study
1. A researcher is interested in whether listening to different types of music or no music while taking a test affects test scores. Students are randomly assigned to one of three groups: The first group takes a test without listening to an iPod, the second group takes the same test while listening to classical music on an iPod, and the third group takes the test while listening to rock music on an iPod. The researcher compares the test scores across the three groups.
2. A psychologist is interested in gender and cognition. She collects data on a large sample of siblings, recording their gender, birth order, and IQ.
3. A professor of ophthalmology is interested in developmental precursors of vision disorders. He collects data from a sample of teenagers on right-eye vision, left-eye vision, and whether the bedroom light was kept off or on as they slept during the night as babies.
Answer:
1. Experimental
2. Correlational
3. Experimental.
Step-by-step explanation:
1. Experimental.
Researches are interested on finding the effects of music on a test.
2. Correlational
Researchers are interested on finding the correlation of the gender and cognition from different samples
3. Experimental
The Researcher wants to know the effects of bedroom light.
Given AB intersects DE at point C. prove: DCB = ECA. What is the missing reason in step 5
Answer: the answer is linear pair
Step-by-step explanation:
Answer:
Linear pair postulate
Step-by-step explanation:
Please answer this correctly
Answer:
First we need to calculate 1 part.
Calculate big part first
13*15 = 195
7*12 = 84
195+84=279
279
279 is answer
Answer: 279 yd^2
Step-by-step explanation:
Separate this into two separate rectangles: the larger top rectangle (13 yd x 15 yd) and the smaller bottom rectangle (12 yd x 7 yd).
area of rectangle 1 + area of rectangle 2 = total area of figure
b1(h1) + b2(h2) = total area
13(15) + 7(12) = total area
195 + 84 = total area
279 yd^2 = total area
someone plz help asap plz
Answer:
a) 6
b) 10
Step-by-step explanation:
a) The area of a rhombus is half the product of the diagonals, meaning that the area of the shaded part is 4*3/2=6 square meters.
b) To find the area of the white background, you need to find the area of the full rectangle, and then to find the area of both rhombii. The area of the black rhombus is 2*4/2=4 square meters. The area of the full rectangle is 4*5=20 units. Subtracting the areas of the two rhombii, you get an area for the white background of 20-6-4=10 square meters. Hope this helps!
In October of 2012, Apple introduced a much smaller variant of the Apple iPad, known at the iPad Mini. Weighing less than 11 ounces, it was about 50% lighter than the standard iPad. Battery tests for the iPad Mini showed a mean life of 10.25 hours (The Wall Street Journal, October 31, 2012). Assume that battery life of the iPad Mini is uniformly distributed between 8.5 and 12 hours.
a. Give a mathematical expression for the probability density function of battery life.
b. What is the probability that the battery life for an iPad Mini will be 10 hours or less (to 4 decimals)?
c. What is the probability that the battery life for an iPad Mini will be at least 11 hours (to 4 decimals)?
d. What is the probability that the battery life for an iPad Mini will be between 9.5 and 11.5 hours (to 4 decimals)?
e. In a shipment of 100 iPad Minis, how many should have a battery life of at least 9 hours (to nearest whole value)?
Answer:
a. [tex]f_X(x) = \dfrac{1}{3.5}8.5<x<12[/tex]
b. the probability that the battery life for an iPad Mini will be 10 hours or less is 0.4286 which is about 42.86%
c. the probability that the battery life for an iPad Mini will be at least 11 hours is 0.2857 which is about 28.57 %
d. the probability that the battery life for an iPad Mini will be between 9.5 and 11.5 hours is 0.5714 which is about 57.14%
e. 86 should have a battery life of at least 9 hours
Step-by-step explanation:
From the given information;
Let X represent the continuous random variable with uniform distribution U (A, B) . Therefore the probability density function can now be determined as :
[tex]f_X(x) = \dfrac{1}{B-A}A<x<B[/tex]
where A and B are the two parameters of the uniform distribution
From the question;
Assume that battery life of the iPad Mini is uniformly distributed between 8.5 and 12 hours
So; Let A = 8,5 and B = 12
Therefore; the mathematical expression for the probability density function of battery life is :
[tex]f_X(x) = \dfrac{1}{12-8.5}8.5<x<12[/tex]
[tex]f_X(x) = \dfrac{1}{3.5}8.5<x<12[/tex]
b. What is the probability that the battery life for an iPad Mini will be 10 hours or less (to 4 decimals)?
The probability that the battery life for an iPad Mini will be 10 hours or less can be calculated as:
F(x) = P(X ≤x)
[tex]F(x) = \dfrac{x-A}{B-A}[/tex]
[tex]F(10) = \dfrac{10-8.5}{12-8.5}[/tex]
F(10) = 0.4286
the probability that the battery life for an iPad Mini will be 10 hours or less is 0.4286 which is about 42.86%
c. What is the probability that the battery life for an iPad Mini will be at least 11 hours (to 4 decimals)?
The battery life for an iPad Mini will be at least 11 hours is calculated as follows:
[tex]P(X\geq11) = \int\limits^{12}_{11} {\dfrac{1}{3.5}} \, dx[/tex]
[tex]P(X\geq11) = {\dfrac{1}{3.5}} (x)^{12}_{11}[/tex]
[tex]P(X\geq11) = {\dfrac{1}{3.5}} (12-11)[/tex]
[tex]P(X\geq11) = {\dfrac{1}{3.5}} (1)[/tex]
[tex]P(X\geq11) = 0.2857[/tex]
the probability that the battery life for an iPad Mini will be at least 11 hours is 0.2857 which is about 28.57 %
d. What is the probability that the battery life for an iPad Mini will be between 9.5 and 11.5 hours (to 4 decimals)?
[tex]P(9.5 \leq X\leq11.5) =\int\limits^{11.5}_{9.5} {\dfrac{1}{3.5}} \, dx[/tex]
[tex]P(9.5 \leq X\leq11.5) ={\dfrac{1}{3.5}} \, (x)^{11.5}_{9.5}[/tex]
[tex]P(9.5 \leq X\leq11.5) ={\dfrac{1}{3.5}} (11.5-9.5)[/tex]
[tex]P(9.5 \leq X\leq11.5) ={\dfrac{1}{3.5}} (2)[/tex]
[tex]P(9.5 \leq X\leq11.5) =0.2857* (2)[/tex]
[tex]P(9.5 \leq X\leq11.5) =0.5714[/tex]
Hence; the probability that the battery life for an iPad Mini will be between 9.5 and 11.5 hours is 0.5714 which is about 57.14%
e. In a shipment of 100 iPad Minis, how many should have a battery life of at least 9 hours (to nearest whole value)?
The probability that battery life of at least 9 hours is calculated as:
[tex]P(X \geq 9) = \int\limits^{12}_{9} {\dfrac{1}{3.5}} \, dx[/tex]
[tex]P(X \geq 9) = {\dfrac{1}{3.5}}(x)^{12}_{9}[/tex]
[tex]P(X \geq 9) = {\dfrac{1}{3.5}}(12-9)[/tex]
[tex]P(X \geq 9) = {\dfrac{1}{3.5}}(3)[/tex]
[tex]P(X \geq 9) = 0.2857*}(3)[/tex]
[tex]P(X \geq 9) = 0.8571[/tex]
NOW; The Number of iPad that should have a battery life of at least 9 hours is calculated as:
n = 100(0.8571)
n = 85.71
n ≅ 86
Thus , 86 should have a battery life of at least 9 hours
Can you please help me with this
Answer:
-The total area of a Rectangular Prism:
[tex]A = 366[/tex] [tex]in^{2}[/tex]
Step-by-step explanation:
-To find the total area of a rectangular prism, you need this formula:
[tex]A = 2(l \cdot w + l \cdot h + w \cdot h)[/tex]
[tex]l =[/tex] Length
[tex]w =[/tex] Width
[tex]h =[/tex] Height
-Apply the length, width and height for the formula:
[tex]A = 2(11 \cdot 8 + 11 \cdot 5 + 8 \cdot 5)[/tex]
[tex]l =[/tex] 11 in
[tex]w =[/tex] 8 in
[tex]h =[/tex] 5 in
-Then, solve for the area:
[tex]A = 2(11 \cdot 8 + 11 \cdot 5 + 8 \cdot 5)[/tex]
[tex]A = 2(88 + 55 + 40)[/tex]
[tex]A = 2(143 + 40)[/tex]
[tex]A = 2 \times 183[/tex]
[tex]A = 366[/tex]
So, the total area would be [tex]366[/tex] [tex]in ^{2}[/tex].
The lengths of text messages are normally distributed with a population standard deviation of 6 characters and an unknown population mean. If a random sample of 21 text messages is taken and results in a sample mean of 30 characters, find a 80% confidence interval for the population mean. Round your answers to two decimal places. z0.10 z0.05 z0.04 z0.025 z0.01 z0.005 1.282 1.645 1.751 1.960 2.326 2.576
Answer:
The 80% confidence interval for the population mean is between 28.32 characters and 31.68 characters.
Step-by-step explanation:
We have the standard deviation for the population, so we can use the normal distribution. If we had the standard deviation for the sample, we would have to use the t-distribution.
We have that to find our [tex]\alpha[/tex] level, that is the subtraction of 1 by the confidence interval divided by 2. So:
[tex]\alpha = \frac{1-0.8}{2} = 0.1[/tex]
Now, we have to find z in the Ztable as such z has a pvalue of [tex]1-\alpha[/tex].
So it is z with a pvalue of [tex]1-0.5 = 0.9[/tex], so [tex]z = 1.282[/tex]
Now, find the margin of error M as such
[tex]M = z*\frac{\sigma}{\sqrt{n}}[/tex]
In which [tex]\sigma[/tex] is the standard deviation of the population and n is the size of the sample.
[tex]M = 1.282*\frac{6}{\sqrt{21}} = 1.68[/tex]
The lower end of the interval is the sample mean subtracted by M. So it is 30 - 1.68 = 28.32 characters.
The upper end of the interval is the sample mean added to M. So it is 30 + 1.68 = 31.68 characters.
The 80% confidence interval for the population mean is between 28.32 characters and 31.68 characters.
Graph g(x)=f(x+1) when f(x) =4x-2
[tex]g(x)=4(x+1)-2[/tex]
[tex]g(x)=4x+4-2[/tex]
[tex]g(x)=4x+2[/tex]
Image attached below for graph.
What’s the correct answer for this?
Answer:
(0,2)
Step-by-step explanation:
2:4 means one part is 2/(2+4)=1/3 of AB and the other part is 2/3 of AB
Add 1/3 of the distance from -2 to 4. (1/3)(4+2)=2. -2+2=0 The x coordinate is 0
Subtract 1/3 of the distance from 6 to -6, (1/3)6+6)=4 6-4=2 The y coordinate is 2
The point is (0,2)
A company that manufactures toothpaste is studying five different package designs.Assuming that one design is just as likely to be selected by a consumer as any other design, what selection probability would you assign to each of the package designs (to 2 decimals)
Answer:
The selection probability to be assigned to each of the package designs is 0.20
Step-by-step explanation:
Firstly, we need to assume that one design is just as likely to be selected by a consumer as any other design
so the probability of selecting any of the design is same and that is 1/5 = 0.20
Thus, what we are trying to say is that each of the package designs have an equal selection probability of 0.20
Find the value of x in the figure below. Round to the nearest tenth.
Answer:
16
Step-by-step explanation:
We can find x using tan 40° which can be represented as x/20. tan 40° is also equal to about 0.8 so that means x / 20 = 0.8 and x = 16.
in the formula C=5/9(F-32),If C=35, then F=?
Step-by-step explanation:
Hope this helps
Hope this is correct
Answer:
F = 95°
Step-by-step explanation:
[tex]C=\frac{5}{9}(F-32)[/tex] is the formula to convert Fahrenheit to Celsius
If we have C = 35, we just need to plug in this number to its corresponding variable and then solve for F
[tex]35=\frac{5}{9}(F-32)[/tex] then we need to multiply both sides of the equation by 9 to get rid of the fraction on the right side[tex]35(9)=[\frac{5}{9}(F-32)](9)[/tex] then simplifies to [tex]315=(5)(F-32)[/tex] Now we can distribute the 5 on the right side to the (F - 32) to get 315 = 5F - 160Adding 160 to both sides we get 475 = 5FDividing both sides by 5 we get 95 = FIn planning a restaurant, it is estimated that a profit of $8 per seat will be made if the number of seats is no more than 50 inclusive. On the other hand, the profit on each seat will decrease 10 cents for each seat above 50.
a) Find the number of seats that will produce the maximum profit.
b) What is the maximum profit?
Answer:
a. 65 seats
b. $422.50
Step-by-step explanation:
We have the following two functions:
8 * x, {0 <= x <= 50}
x * (8 - 0.1 * (x - 50)), {x> 50}, solving we have:
-0.1 * x ^ 2 + 13 * x, {x> 50}
Now we derive both functions and we are left with:
8, {0 <= x <= 50}
-0.2 * x + 13 {x> 50}
we cannot equal to 0 the first function that is equal to 0, because it would be inconsistent, therefore we equal the second function to 0:
-0.2 * x + 13 = 0
0.2 * x = - 13
x = -13 / -0.2
x = 65
Now, test for increasing and decreasing on the intervals (0.65) and (65, infinity)
p '(60) = -0.2 * (60) + 13 = 1
since this value is positive the profit is increasing on (0.65)
p '(70) = -0.2 * (70) + 13 = -1
becuase this value is negative the profit is decreasing on (65, infinity)
Therefore 65 seats are needed to maximize profit
The maximum value would be:
P (65) = 0.1 * (65 ^ 2) + 13 * 65 = 422.5
That is, the maximum value is $ 422.50
What is the equation of a line with a slope of -2 that passes through the point(6,8)
Step-by-step explanation:
work is shown and pictured
A study conducted at a certain high school shows that 72% of its graduates enroll at a college. Find the probability that among 4 randomly selected graduates, at least one of them enrolls in college.
Answer:
[tex] P(X \geq 1) =1-P(X<1) =1-P(X=0) [/tex]
And we can use the probability mass function and we got:
[tex]P(X=0)=(4C0)(0.72)^0 (1-0.72)^{4-0}=0.00615[/tex]
And replacing we got:
[tex] P(X \geq 1) = 1-0.00615 = 0.99385[/tex]
Step-by-step explanation:
Let X the random variable of interest "number of graduates who enroll in college", on this case we now that:
[tex]X \sim Binom(n=4, p=0.72)[/tex]
The probability mass function for the Binomial distribution is given as:
[tex]P(X)=(nCx)(p)^x (1-p)^{n-x}[/tex]
Where (nCx) means combinatory and it's given by this formula:
[tex]nCx=\frac{n!}{(n-x)! x!}[/tex]
We want to find the following probability:
[tex] P(X \geq 1)[/tex]
And we can use the complement rule and we got:
[tex] P(X \geq 1) =1-P(X<1) =1-P(X=0) [/tex]
And we can use the probability mass function and we got:
[tex]P(X=0)=(4C0)(0.72)^0 (1-0.72)^{4-0}=0.00615[/tex]
And replacing we got:
[tex] P(X \geq 1) = 1-0.00615 = 0.99385[/tex]
What’s the correct answer for this? Select all that apply
Answer:
B and C
Step-by-step explanation:
The correct options are :
A cross-section that is perpendicular to the base of a cube.
A cross-section that is perpendicular to the base of a cylinder whose base diameter and height are the same.
In both the cases the length and the width of the section are equal
What percent of forty-eight is thirty?
Answer:
P = 62.5 %
Step-by-step explanation:
Of means multiply and is means equals
P * 48 = 30
Divide each side by 48
P = 30/48
P = .625
Change to percent form
P = 62.5 %
Answer:
62.5%
Step-by-step explanation:
30 is 62.5% of 48 since:
30÷48=0.625
0.625×100=62.5%
Dustin is buying carpet for the living room. How many square feet of carpet will he need to buy?
Complete Question:
Dustin is buying carpet for the living room. If the length of the room is 21 ft and the width
is 11 ft, how many square feet of carpet does he need to buy?
Answer:
231 ft²
Step-by-step explanation:
==>GIVEN:
Length of room (L) = 21 ft
Width of room (W) = 11 ft
==>REQUIRED:
Square feet of carpet to be bought = area of the rectangular room
==>SOLUTION:
The room to be covered with carpet is rectangular in shape. In order to ascertain the square feet of carpet to be bought, we need to calculate the area of the room by using the formula for area of rectangle.
Thus, area of rectangle (A) = Length (L) × Width (W)
A = 21 × 11
A = 231 ft²
Square feet of carpet to be bought = 231 ft²