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.