Question

A survey is being planned to determine the mean amount of time corporation executives watch television. A pilot survey indicated that the mean time per week is 12 hours, with a standard deviation of 3.5 hours. It is desired to estimate the mean viewing time within one-quarter hour. The 90% level of confidence is to be used. How many executives should be surveyed? (Round your z-score to 2 decimal places and round your final answer to the next whole number.)

Answer 1

Answer

we have to find the sample size n

we have margin of error (ME)= 1/4 hour or 0.25

standard deviation = 3.5 and mean= 12

we have to use 90% confidence level, using z distribution for 90% confidence level, we get z critical = 1.64

Formula for the sample size calculation is given as

setting the given values

we get

Rounding it off to the next whole number, we get n = 528

So, required sample size is n =528