Length of pregnancy have a mean of 268 days and a standard deviation of 15 days. A researcher is concerned that people who have taken a particular drug in the past might have shorter length of pregnancies. The researchers sample n=25 people who had taken the drug and recently given birth and found they had an average length of pregnancy of 262.9 days do these data support the researchers claim? (Use a equals 0.01, one tail Test)

Determine the zCrit value ,

calculate standard error of length of pregnancy calculate the observed Z score for the sample mean ,calculate the effect size using Cohen's d,

what conclusion can the researcher make from these data?