Question 1117595
Most statisticians will say that as large a sample as one can get, but n=30 has been used because even a t-distribution will be within 2 per cent of normality.
t(df=44)=(xbar-mean)/s/sqrt(n)
=(15-16.2)/3.5/sqrt(45)
=-1.2*sqrt(45)/3.5
=-2.30
This is a probability of 0.0130