Question 1183497
Assuming random sample
Ho: mu is 90
Ha: mu is not = 90 (two way test)
alpha can be 0.05 p{reject Ho|Ho true}
test is a z
critical value reject Ho if |z| > 1.96
calculation, z=(x bar-mean)/sigma/sqrt(n)
z=3.3*sqrt(25)/15
=16.5/15
=1.1
fail to reject Ho at the 5% level; insufficient evidence to reject null hypothesis that mean is truly90