Work sheet #6 STA 2023

For #1 – 5, find and . Round to the thousandths place if necessary.

1) n = 500 and x = 400

2) n = 1000 and x = 250

3) n = 1068 and x = 237

4) n = 777 and x = 543

5) n = 3622 and x = 412

For #6 – 10, find the minimum required sample size for each, rounded to the appropriate whole number.

6) margin of error: 0.025; confidence level: 99%; p = .25

7) margin of error: 0.04; confidence level 98%; p = .7

8) margin of error: 3%; confidence level 95%; p = .5

9) margin of error 2%; confidence level 97%; p = .15

10) margin of error 1.5%; confidence level 96%; p = .66

For # 11 – 15, find the minimum required sample size for each, rounded to the appropriate whole number.

11) The standard IQ test has a mean of 100 and s = 15. We want to be 98% confident that our sample mean is within 1.5 IQ points of the true mean.

12) A new test of spatial perception is developed for commercial pilots & we want to estimate the mean with 96% confidence and we want to be no more than 5 points off. A preliminary study had s = 40.

13) We want to be 99% confident that the sample mean for quarters is within 0.025 grams of the true mean. s has previously been found to be 0.068. This is very important for the vending machine company.

14) We want to find the mean amount of money spent by movie patrons with a margin of error of $0.25, a 98% confidence level, and a pilot survey found s = $3.

15) We want to estimate the mean income for the first year of work for college graduates who took a Stats course. We want 95% confidence level that the mean is within $500 of the true mean. A study 5 years ago had s = $6250.