Aresearcher wants to estimate the mean weekly family expenditure on clothing purchases and maintenance. first, she needs to determine the number of families that must be sampled, in order to estimate the mean weekly expenditure on clothing to within $15 at alpha = 0.01. from prior similar studies she is confident that the standard deviation of weekly family expenditures on clothing purchases and maintenance is $125. the required sample size to be taken

a. 21
b. 22
c. 461
d. 460
e. 460.46