1) In order to set rates, an insurance company is trying to estimate the number of sick days that full time workers at an auto repair shop take each year. A previous study indicated the standard deviation was 2.8 days. How large a sample must be selected if the company wants to be 95% confident that the true mean differs from the sample mean no more than 1 day?
A) 1024 B) 512 C)313 D)141
2) A manufacturer of golf equipment wishes to estimate the number of left handed golfers. How large a sample is needed to be 98% confident that the sample proportion will not differ from the true proportion by more than 5%? A previous study indicates that the proportion of left hand golfers is 8%.
3) Fifty five percent of registered voters in a congressional district are registered Democrats. The Republican candidate takes a poll to assess his chances in a two candidate race. He polls 1200 potential voters and finds that 621 plan to vote for the Democratic candidate. Does the Republican candidate have a chance to win? Use a=0.05
The solution determines the sample size for an insurance company, golf equipment manufacturer, and political candidates.