Answer:
[tex]C(t) =\dfrac{ r}{k} - \left (\dfrac{r-kC_{0}}{k} \right )e^{ -kt}[/tex]
[tex]C(t) =\dfrac{ r}{k}- e^{ -kt}[/tex] ,thus, the function is said to be an increasing function.
Step-by-step explanation:
Given that:
[tex]\dfrac{dC}{dt}= r-kC[/tex]
[tex]\dfrac{dC}{r-kC}= dt[/tex]
Taking integration on both sides ;
[tex]\int\limits\dfrac{dC}{r-kC}= \int\limits \ dt[/tex]
[tex]- \dfrac{1}{k}In (r-kC)= t +D[/tex]
[tex]In(r-kC) = -kt - kD \\ \\ r- kC = e^{-kt - kD} \\ \\ r- kC = e^{-kt} e^{ - kD} \\ \\r- kC = Ae^{-kt} \\ \\ kC = r - Ae^{-kt} \\ \\ C = \dfrac{r}{k} - \dfrac{A}{k}e ^{-kt} \\ \\[/tex]
[tex]C(t) =\frac{ r}{k} - \frac{A}{k}e^{ -kt}[/tex]
here;
A is an integration constant
In order to determine A, we have [tex]C(0) = C0[/tex]
[tex]C(0) =\frac{ r}{k} - \frac{A}{k}e^{0}[/tex]
[tex]C_0 =\frac{r}{k}- \frac{A}{k}[/tex]
[tex]C_{0} =\frac{ r-A}{k}[/tex]
[tex]kC_{0} =r-A[/tex]
[tex]A =r-kC_{0}[/tex]
Thus:
[tex]C(t) =\dfrac{ r}{k} - \left (\dfrac{r-kC_{0}}{k} \right )e^{ -kt}[/tex]
2. Assuming that C0 < r/k, find lim t→[infinity] C(t) and interpret your answer
[tex]C_{0} < \lim_{t \to \infty }C(t) \\ \\C_0 < \dfrac{r}{k} \\ \\kC_0 <r[/tex]
The equation for C(t) can be rewritten as :
[tex]C(t) =\dfrac{ r}{k} - \left (\dfrac{r-kC_{0}}{k} \right )e^{ -kt}C(t) =\dfrac{ r}{k} - \left (+ve \right )e^{ -kt} \\ \\C(t) =\dfrac{ r}{k}- e^{ -kt}[/tex]
Thus; the function is said to be an increasing function.
How do you write or break down this decimal:
45.50 =
Step-by-step explanation:
45.50
Converting decimal
45.50 x 100 = 4550
What is an equation of the line that is parallel to y = 9 – 5x and passes through (0, 8)?
Answer:
y = 8 - 5x
Step-by-step explanation:
both equations shares the same gradient as they are parallel
from y= 9-5x, the gradient is -5
subst x = 0, y=8, and m= -5 into the y = mx + c to find the value of c
8 = (-5)(0) + c
c= 8
therefore the eqn is y = 8 - 5x
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]
Help me please and thanks
Hey there! :)
Answer:
B.
Step-by-step explanation:
To find the solution to the inequality, we can begin by solving for 'x':
2x + 1 ≥ 3
Subtract 1 from both sides:
2x ≥ 2
Divide both sides by 2:
x ≥ 1.
This means that the graph must contain all values of x greater or equal to one. The only number line that shows solutions greater than 1 is B.
An accident Investigator measured the skid marks of one of the vehicles involved in an accident. The length of the skid
marks, d, was 117ft. Use the formula s = 24d to find s, the speed of the vehicle before the brakes were applied. Fund
Answer:
2,808
Step-by-step explanation:
since 117 = d then we would just plug that into the equation of s = 24d and get s = 24(117), after that you would just solve.
Answer:
53
Step-by-step explanation:
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
prove each identify
cos X(tanX+cotX) =cscX
Answer:
Step-by-step explanation:
cos X(tanX+cotX) =cscX
cos X(sinx/cosx +cosx/sinx) =cscx
cos X (sin²+cos²/cossin)=cscx
cosx(1/cossin)=cscx
cross out cosines
1/sinx=cscx
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.
• Write this number as a fraction:178.25
Answer: 178 1/4 or 713/4
Step-by-step explanation:
178.25 = 178+0.25 = 178+25/100
gcd(25,100) = 25
178.25 = 178+(25/25)/(100/25) = 178+1/4 = 713/4
Write the quotient in simplest form. Type answer as integer or a fraction
Answer:
[tex]-\dfrac{1}{26}[/tex]
Step-by-step explanation:
[tex]-\dfrac{12}{13}\div 24=\\\\-\dfrac{12}{13} \times \dfrac{1}{24}=\\\\-\dfrac{12}{13\times 24}=\\\\-\dfrac{1}{26}[/tex]
Hope this helps!
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.
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.
A researcher has developed a new drug designed to reduce blood pressure. In an experiment, 21 subjects were assigned randomly to the treatment group and received the new experimental drug. Based on these data, the computed two-sample t statistic is:
Answer:
I think the complete question should be:
A researcher has developed a new drug designed to reduce blood pressure. In an experiment, 21 subjects were assigned randomly to the treatment group and received the new experimental drug. The other 23 subjects were assigned to the control group and received a standard well known treatment. After a suitable period of time, the reduction in blood pressure for each subject was recorded.
Treatment group n = 21, x1 mean = 23.48, sd = 8.01
Control group n = 23, x2 = 18.52, sd = 7.15
Based on these data, the computed two-sample t statistic is:
Step-by-step explanation:
Since the variances to be calculated from the sd are unequal we use this formula:
t statistics = (x1 - x2) / [(sd1²/n1) + (sd2²/n2) where n1 = 21, x1 mean = 23.48, sd1 = 8.01, n2 = 23, x2 = 18.52, sd2 = 7.15
Thus, we have
test statistic= (23.48-18.52) / [(8.01²/21) + (7.15²/23)]
Test statistics = 4.96 / (324.36/21)+(51.12/23)]
Test statistics = 4.96/ (15.45+2.43)
t statistic = 4.96 / 17.88
t statistics = 0.2774
I hope that helps, you can use this to solve for tours if the values are not the same
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.
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
Breakfast Bar’s scrambled egg recipe uses 8 eggs to feed 5 people. How many eggs are they going to need to serve 100 people on Saturday morning?
Explain the steps you would use to solve the problem.
Answer:
800 eggs
Step-by-step explanation:
You would first thing about the starting numbers, Then look at the number 100 and multiply by 8. This would give you 800. This means that you will need 800 eggs to serve 100 people.
Brainliest is greatly appreciated
Answered by: Skylar
6/8/2020
9:59 AM (Eastern Time)
Answer:
the answer is 12.5 i know because i divided 100 by 8 and got 12.5 then multiply then got 100
Step-by-step explanation:
got it right just did the test
Can someone plz help me solved this problem I need help ASAP plz help me! Will mark you as brainiest!
Answer: h = -(16t + 3)(t - 2)
h(0) = 6
h(1) = 19
h(2) = 0
Step-by-step explanation:
Factor the equation by finding two numbers whose
product = a×c and sum = b, then replace the b value with those two numbers and factor the equation.
h = -16t² + 29t + 6
a=-16 b=29 c=6 a×c = -96 b = 29
32 × -3 = 96 32 + (-3) = 29
h = -16t² + 32t -3t + 6
h = -16t(t - 2) -3(t - 2)
h = (-16t - 3) (t - 2)
h = -(16t + 3)(t - 2)
h(0) = -[16(0) + 3] [0 - 2]
= -(3)(-2)
= 6
h(1) = -[16(1) + 3] [1 - 2]
= -(19)(-1)
= 19
h(2) = -[16(2) + 3] [2 - 2]
= -(35)(0)
= 0
An HP laser printer is advertised to print text documents at a speed of 18 ppm (pages per minute). The manufacturer tells you that the printing speed is actually a Normal random variable with a mean of 17.48 ppm and a standard deviation of 3.25 ppm. Suppose that you draw a random sample of 10 printers.
Using the information about the distribution of the printing speeds given by the manufacturer, find the probability that the mean printing speed of the sample is greater than 18.06 ppm. (Please carry answers to at least six decimal places in intermediate steps. Give your final answer to the nearest three decimal places). Probability (as a proportion)
Answer:
0.288
Step-by-step explanation:
To solve this question, we need to understand the normal probability distribution and the central limit theorem.
Normal probability distribution
Problems of normally distributed samples are solved using 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.
Central Limit Theorem
The Central Limit Theorem estabilishes that, for a normally distributed random variable X, with mean [tex]\mu[/tex] and standard deviation [tex]\sigma[/tex], the sampling distribution of the sample means with size n can be approximated to a normal distribution with mean [tex]\mu[/tex] and standard deviation [tex]s = \frac{\sigma}{\sqrt{n}}[/tex].
For a skewed variable, the Central Limit Theorem can also be applied, as long as n is at least 30.
In this question, we have that:
[tex]\mu = 17.48, \sigma = 3.25, n = 10, s = \frac{3.25}{\sqrt{10}} = 1.027740[/tex]
Find the probability that the mean printing speed of the sample is greater than 18.06 ppm.
This is 1 subtracted by the pvalue of Z when X = 18.06. So
[tex]Z = \frac{X - \mu}{\sigma}[/tex]
By the Central Limit Theorem
[tex]Z = \frac{X - \mu}{s}[/tex]
[tex]Z = \frac{18.06 - 17.48}{1.027740}[/tex]
[tex]Z = 0.56[/tex]
[tex]Z = 0.56[/tex] has a pvalue of 0.712
1 - 0.712 = 0.288
The answer is 0.288
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
Ralph is 3 times as old as Sara. In 4 years, Ralph will be only tice as old as Sara will be then.
If x represents Sara's age now, which of the following expressions represents Ralph's age in four years?
A. 3x
B. 2x+4
C. 3x+4
Answer:
In 6 years, Ralph will be only twice as old as Sara
Step-by-step explanation:
Answer:
The answer is C, 3x+4
Step-by-step explanation:
The “in four years” part translates to +4. The 3x translates to 3 times his current age. Hope this helped :)
A gum ball machine has 22 red 18 white 10 blue and 23 green. What chances of pulling out a red
Step-by-step explanation:
Total gum balls = 22 + 18 + 10 + 23 = 73
Probability of red gum = 22/73
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.
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%
A florist currently makes a profit of $20 on each of her celebration bouquets and sells a average of 30 bouquets every week
Answer:
Step-by-step explanation:
THIS IS THE COMPLETE QUESTION BELOW;
A florist currently makes a profit of $20 on each of her celebration bouquets and sells an average of 30 bouquets every week. She noticed that when she reduces the price such that she earns $1 less in profit from each bouquet, she then sells three more bouquets per week. The relationship between her weekly profit, P(x), after x one-dollar decreases is shown in the graph below.
CHECK THE ATTACHMENT FOR THE GRAPH
EXPLANATION;
FIRST QUESTION:
From the graph maximum profit is the value gotten where p(X) has maximum value, and the maximum value is observed at y- axis at P(X)to be 675.
Thefore, maximum profit the florist will earn from celebration bouquet is $675.
SECOND QUESTION:
Break even is the exact point that profit p(x) is observed as zero.
Checking the given g graph the point where there is zero value of p(X) is observed at x=20 and x= -10 but we can only pick the positive value which is x=20
Therefore, the florist will break even after 20 one- dollar decreases
THIRD QUESTION;
The interval of number of one dollar decreases can be observed at the point where we have the value of P(x) been more than zero, looking at the given graph, the P(x) has its value greater than zero at the interval 0 to 20.Therefore, it can be concluded that the interval of number of one dollar decreases for which the florist makes a profit from celebration bouquet is (0, 20)
Answer:
Step-by-step explanation:
A market research firm supplies manufacturers with estimates of the retail sales of their products from samples of retail stores. Marketing managers are prone to look at the estimate and ignore sampling error. A random sample of 36 stores this year shows mean sales of 53 units of a small appliance with a standard deviation of 12 units. During the same point in time last year, a random sample of 49 stores had mean sales of 41 units with standard deviation 6 units.
It is of interest to construct a 95 percent confidence interval for the difference in population means ?1??2, where ?1 is the mean of this year's sales and ?2 is the mean of last year's sales.
Enter values below rounded to three decimal places.
(a) The estimate is: _________ .
(b) The standard error is: ____________________ .
Answer:
The 95% confidence interval for the difference of means is (7.67, 16.33).
The estimate is Md = 12.
The standard error is sM_d = 2.176.
Step-by-step explanation:
We have to calculate a 95% confidence interval for the difference between means.
The sample 1 (this year's sales), of size n1=36 has a mean of 53 and a standard deviation of 12.
The sample 2 (last year's sales), of size n2=49 has a mean of 41 and a standard deviation of 6.
The difference between sample means is Md=12.
[tex]M_d=M_1-M_2=53-41=12[/tex]
The estimated standard error of the difference between means is computed using the formula:
[tex]s_{M_d}=\sqrt{\dfrac{\sigma_1^2}{n_1}+\dfrac{\sigma_2^2}{n_2}}=\sqrt{\dfrac{12^2}{36}+\dfrac{6^2}{49}}\\\\\\s_{M_d}=\sqrt{4+0.735}=\sqrt{4.735}=2.176[/tex]
The degrees of freedom are:
[tex]df=n_1+n_2-1=36+49-2=83[/tex]
The critical t-value for a 95% confidence interval and 83 degrees of fredom is t=1.989.
The margin of error (MOE) can be calculated as:
[tex]MOE=t \cdot s_{M_d}=1.989 \cdot 2.176=4.328[/tex]
Then, the lower and upper bounds of the confidence interval are:
[tex]LL=M_d-t \cdot s_{M_d} = 12-4.328=7.67\\\\UL=M_d+t \cdot s_{M_d} = 12+4.328=16.33[/tex]
The 95% confidence interval for the difference of means is (7.67, 16.33).
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
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:
Use Newton's method with initial approximation x1 = 1 to find x2, the second approximation to the root of the equation x4 − x − 3 = 0. (Round your answer to four decimal places.) x2 =?
Answer:
[tex]x_{2} = 0.0000[/tex]
Step-by-step explanation:
The formula for the Newton's method is:
[tex]x_{i+1} = x_{i} + \frac{f(x_{i})}{f'(x_{i})}[/tex]
Where [tex]f' (x_{i})[/tex] is the first derivative of the function evaluated in [tex]x_{i}[/tex].
[tex]x_{i+1} = x_{i} + \frac{x_{i}^{4}-x_{i}-3}{4\cdot x_{i}^{3}-1}[/tex]
Lastly, the value of [tex]x_{2}[/tex] is determined by replacing [tex]x_{1}[/tex] with its numerical value:
[tex]x_{2} = x_{1} + \frac{x_{1}^{4}-x_{1}-3}{4\cdot x_{1}^{3}-1}[/tex]
[tex]x_{2} = 1.0000 + \frac{1.0000^{4}-1.0000-3}{4\cdot (1.0000)^{3}-1}[/tex]
[tex]x_{2} = 0.0000[/tex]
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!
In 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