Question

Annual starting salaries for college graduates with degrees in business administration are generally expected to be between $20,000 and $50,000 . Assume that a 95% confidence interval estimate of the population mean annual starting salary is desired.

a. What is the planning value for the population standard deviation? _____

b. How large a sample should be taken if the desired margin of error is $300? Round your answer to next whole number.

____________

$250? _______

$140? _______

c. Would you recommend trying to obtain the $140 margin of error? Explain.
- Select your answer -Yes, it always better to be more accurate.No, the sample size would probably be too time consuming and costly.Item 5

Answer 1

Annual starting salaries for college graduates with degrees in business administration are generally expected to be between $20,000 and $50,000

so the range = (50000 - 20000) = 30000

the confidence interval (c) = 95 % = 0.95

a).the standard deviation be:-

[ we know that approximately 95% of the data is within two standard deviations (higher or lower) from the mean.

so,for 95 % ci, the sd is range divided by 4]

b). the formula of sample size is :-

we know that,the critical value of z for 95 % confidence interval, both -side be:-

so, the sample sizes are as follows:-

margin of error (E)	sample size calculation	sample size(n)
300		2401
250		3458
140		11025

c). the option be:-

No, the sample size would probably be too time consuming and costly.

[ as 11025 is a large sample size.. it will cost a huge amount and will be too time consuming]

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