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Lelu [443]
2 years ago
10

Fast-food restaurants spend quite a bit of time studying the amount of time cars spend in their drive-throughs. Certainly, the f

aster the cars get through the drive-through, the more the opportunity for making money. QSR Magazine studied drive-through times for fast-food restaurants and found Wendy’s had the best time, with a mean time spent in the drive-through of 138.5 seconds. Assuming drive-through times are normally distributed with a standard deviation of 29 seconds, answer the following.
(a) Management wants to set a wait time over which a customer will not have to pay for their food. Of course, management wants to set that wait time to the 99th percentile. Find the X for the 99th percentile. (Hint: 99% = 0.9900). Round to the nearest whole second. Sullivan, Michael III. Fundamentals of Statistics: #40 (Ch 7.2). Pearson Education. Kindle Edition.
Mathematics
1 answer:
melisa1 [442]2 years ago
4 0

Answer:

For the 99th percentile, we have X = 206 seconds.

Step-by-step explanation:

Problems of normally distributed samples can be solved using the z-score formula.

In a set with mean \mu and standard deviation \sigma, the zscore of a measure X is given by:

Z = \frac{X - \mu}{\sigma}

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 problem, we have that:

\mu = 138.5, \sigma = 29

99th percentile:

Value of X when Z has a pvalue of 0.99. So we use Z = 2.325

Z = \frac{X - \mu}{\sigma}

2.325 = \frac{X - 138.5}{29}

X - 138.5 = 29*2.325

X = 205.92 = 206

For the 99th percentile, we have X = 206 seconds.

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Which real-world story is represented by the addition problem (–2 1/2) + (–3 1/4) = –5 3/4?
allochka39001 [22]

Answer:

A

Step-by-step explanation:

A is the correct answer because the equation matches option A.

(-2 1/2) + (-3 1/4)

The minus sign in -2 1/2 shows that the submarine descended and then descended again with the addition sign. Though the addition sign can mean that it ascended its incorrect.

With the equation in hand, we can prove that option A is correct.

If the submarine descended 2 1/2 miles then here must be a minus sign next to the 2 1/2. But if it ascended then there would've been an addition sign to show that it ascended. The other value - 3 1/4 also shows that it ascended with the help of the addition sign.

Ascends - values increase from smallest to highest.

Descends - values decrease from highest to smallest.

4 0
3 years ago
Which of the following functions are solutions of the differential equation y'' + y = 3 sin x? (select all that apply)
DiKsa [7]

Answer:

C

Step-by-step explanation:

We must compute the derivatives and check if the equation is satisfied.

A. y'=(3\sin x)'=3\cos x. Differentiate again to get y''=(3\cos x)'=-3\sin x, then y''+y=-3\sin x+3\sin x=0\neq 3\sin x so this choice of y doesn't solve the equation.

B. y'=3\sin x+3x\cos x-5\cosx +5x\sin x=(5x+3)\sin x+(3x-5)\cos x and y''=5\sin x+(5x+3)\cos x+3\cos x-(3x-5)\sin x=(10-3x)\sin x+(5x+6)\cos x, then y''+y=10\sin x+6\cos x\neq 3\sin x so y is not a solution

C. y'=\frac{-3}{2}\cos x+\frac{3}{2}x\sin x hence y''=\frac{3}{2}\sin x+\frac{3}{2}\sin x+\frac{3}{2}x\cos x=3\sin x+\frac{3}{2}x\cos x. Then y''+y=3\sin x+\frac{3}{2}x\cos x-\frac{3}{2}x\cos x=3\sin x so y is a solution.

D.y'=-3\sin x and y''=-3\cos x, then y''+y=0 thus y isn't a solution

E. y'=\frac{3}{2}\sin x+\frac{3}{2}x\cos x hence y''=\frac{3}{2}\cos x+\frac{3}{2}\cos x-\frac{3}{2}x\sin x=3\cos x-\frac{3}{2}x\cos x. Then y''+y=3\cos x-\frac{3}{2}x\cos x-\frac{3}{2}x\cos x=3\cos x\neq 3\sin x then y is not a solution.

3 0
3 years ago
Mark had 4 members in his family each of the person get 1/6 what Is the fraction of the tomato use fraction strips
umka21 [38]

If each person got 1/6 then there is still 2/6 left over, =1/3. In fraction strips, we would do

                  1

  1/3         1/3        1/3                                                                 1/3

1/6 1/6   1/6 1/6  1/6 1/6 for the overall tomato and then  1/6 1/6  for the remaining piece of the tomato.

Hope this helps, if you need any more help just comment :)

8 0
3 years ago
Jan conducts an experiment and tosses a coin 40 times. She gets heads 30 times instead of the expected 20. What could be a reaso
Nady [450]

the answer is B. hope i helped

8 0
2 years ago
A circle has an area of 3.14 cm^2 . What is its radius?
Anni [7]

Answer:

Cant be determined

Step-by-step explanation:

You would need the diameter to figure this out

6 0
3 years ago
Read 2 more answers
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