Answer :
The probability that the the sample mean would be less than x=132.25 will be calculated as follows:
z=(x-σ)/μ
μ- mean
σ- standard deviation
z=(132.25-138)/28=-0.2054
thus:
P(X≤x)=0.4207=42.07%
z=(x-σ)/μ
μ- mean
σ- standard deviation
z=(132.25-138)/28=-0.2054
thus:
P(X≤x)=0.4207=42.07%