SOLUTION: I need to understand how to do the step to get the answer, for future question. What are the big corporations doing with their wealth? One way to answer this question is to exam

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Question 878744: I need to understand how to do the step to get the answer, for future question.
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.
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 13 16 5 4 12
Estimate the sample mean, sample variance, and sample standard deviation for profit as percentage of assets. (Round your answers to one decimal place.)

x =
% of assets
s2 =

s =
% of assets

Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!
 

Hi

My recommendation would be an Excel electronic worksheet

0r something similar. Key is: (12.5-8.6)/2 = 1.95 and 8.6+1.95 = 10.55, for ex

x	n	 xn	x -17.43 n(x -17.43)^2	

10.55	13	137.15	-6.88	615.3472	

14.55	16	232.8	-2.88	132.7104	

18.55	5	92.75	1.12	6.272	

22.55	4	90.2	5.12	104.8576	

26.55	12	318.6	9.12	998.0928	

					

	50	871.5	5.6	1857.28 (sum)	

	mean	17.43		37.90367347	Variance sum/(n-1)

				6.156595932	SD (sqrt of variance)