Mathematics, 14.02.2020 01:43 anggar20

What are the big corporations doing with their wealth? One way to answer this question is to examine profits as percentage of assets. A random sample of 50 Fortune 500 companies gave the following information. (Source: Based on information from Fortune 500, Vol. 135, No. 8.) Estimate the sample mean, sample variance, and sample standard deviation for profit as percentage of assets. (Enter your answers to one decimal place.)

Profit as percentage of assets 8.6-12.5 12.6-16.5 16.6-20.5 20.6-24.5 24.6-28.5
Number of companies 15 18 4 3 10

Answers: 2

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Answer from: EBeast7390

$\bar X = \frac{827.5}{50}= 16.55 \approx 16.6$

$s^2 = \frac{15431.13 -\frac{(827.5)^2}{50}}{49}= 35.429 \approx 35.4$

$s = \sqrt{35.429}= 5.952 \approx 6.0$

Step-by-step explanation:

For this case is useful construct the following table:

Class Midpoint (xi) fi xi* fi xi^2* fi

_________________________________________

8.6-12.5 10.55 15 158.25 1669.538

12.6-16.5 14.55 18 261.9 3810.645

16.6-20.5 18.55 4 74.2 1376.41

20.6-24.5 22.55 3 67.65 1525/508

24.6-28.5 26.55 10 265.5 7049.025

_________________________________________

Total 50 827.5 15431.13

For this case the sample mean can be calculated with this formula:

$\bar X=\frac{\sum_{i=1}^n x_i f_i}{n}$

And if we replace we got:

$\bar X = \frac{827.5}{50}= 16.55 \approx 16.6$

For the sample variance we can ise the following formula:

$s^2 = \frac{\sum x^2_i f_i -\frac{(\sum x_i f_i)^2}{n}}{n-1}$

And replacing we got:

$s^2 = \frac{15431.13 -\frac{(827.5)^2}{50}}{49}= 35.429 \approx 35.4$

And for the deviation we just take the square root of the variance and we got:

$s = \sqrt{35.429}= 5.952 \approx 6.0$

Answer from: Quest

answer: sensy

step-by-step explanation:

Answer from: Quest

2 & 7

step-by-step explanation:

he climbs 300 ft/hr at a constant rate. the peak is at 1,500 ft.

when going up, he reaches 600 ft in 2 hours. remember, that he is going in a constant rate. divide 600 with 300:

600/300 = 2

assuming that he takes the same route back (meaning that it's a 1500 ft route back, you can solve.

note also that you are solving when he gets back to 600 ft after he reaches the peak.

first, find the amount of hours it takes to get up the peak. divide the total amount (1500), with the ft/her (300) to get the amount of hours (x):

1500/300 = x

x = 5

it takes jamie 5 hours to get up. now, he is returning down, and reaches 600 (his current destination). remember that he climbs at a constant 300 ft/hr. divide 600 with 300:

600/300 = x

x = 2

now add the two numbers together.

x = 5 + 2 = 7

jamie takes 7 hours to go up the mountain and reach his current position when descending.

(total amount/constant rate) = (time).

remember that it is a constant rate, so in total, when he gets back down the mountain, it will take the same amount of time as when he goes up. the total amount for the round trip is: 5 + 5 = 10.