It costs you $10 to draw a sample size n=1 and measure the attribute of interest. you have a budget of $1,200

a. Do you have sufficient funds to estimate the population mean for the attribute of interest with a 95% confidence interval 4 units width? Assume that sd = 12

n = {[ (Zalpha/2) ^2]*[sd]^2} / se^2

n = (1.96) ^2 * (12) ^2 / (2) ^2

n = 138.297 rounded up to 139

There is not enough funds for this one since you’ll need 139 pieces and it costs 10 a piece, you’ll need 1390.

b. 90% confidence interval

n = {[ (Zalpha/2) ^2]*[sd]^2} / se^2

n = (1.645) ^2 * (12) ^2 / (2) ^2

n=98

There is enough funds since 98 pieces for 10 a piece is equal to 980.