Answer: standard error of mean r* = 1.90
Step-by-step explanation:
The Finite Correction Factor (FPC) is used when you sample without replacement from more than 5% of a finite population.
FPC = √[(N-n )/(N-1)]
N= population size = 250
n= sample size = 50
r* = standard error of mean
r = standard deviation = 15
FPC = √[(250-50)/(250-1)] = 0.896
Standard error of mean using FPC will be given as
r* = (r/√n) × FPC
r* = 15/√50 × 0.896
r* = 1.90