Consider two independentrandom samples of sizesn1= 11andn2= 15, taken from two normally distributed populations.The sample standard deviationsare calculated to bes1= 5.3ands2= 8.7, and the sample meansarex1=71.32 andx2=77.09,respectively.

a)Calculate a point estimate for the difference in population means,12.

Round your response to at least 3 decimal places.

b)Using the Welch approximatetprocedure anda conservative estimate of the degrees of freedom (i.e. the lesser ofn1- 1andn2- 1), what is theappropriatet/2 (alpha/2) value for a 99% confidence interval?

Round your response to at least3 decimal places.

c)Calculate the margin of error for a 99% confidence interval.

Round your response to at least 3 decimal places.