A researcher wishes to estimate the percentage of adults who

A researcher wishes to estimate the percentage of adults who support abolishing the penny. What size sample should be obtained if he wishes the estimate to be within 3 percentage points with 95% confidence if he uses a previous estimate of 34%? he does not use any prior estimates? n = (Round up to the nearest integer.) n = (Round up to the nearest integer.)

Solution

95% cI z alph/2 1.96 Margin of error 3 a) estimate of proportion 0.34 Variance 0.2244/n Std dev 0.4737/rtn Margin of error 0.9284/rtn 0.03 We find n from this rtn> 30.94667 n> 957.6962 n must be atleast 958 95% cI z alph/2 1.96 When no previous estimate is given p is taken as 0.50 Margin of error 3 a) estimate of proportion 0.5 Variance 0.25/n Std dev 0.5/rt n Margin of error 0.98/rtn 0.03 We find n from this rtn> 32.66667 n> 1067.111 n must be atleast 1068