To compare the mean lengths of time to recovery after two surgical procedures I and II,10patients after surgical procedure I were randomly selected, and the length of time to recovery was recorded for each patient. Also10patients after surgical procedure II were

randomly selected, and the length of time to recovery was recorded for each patient. Calculated values of sample mean and sample variances are given in the following table:

Procedure I	Procedure II
x1= 7.7 days	x2= 9.8 days
21S=1.25 days squared	22S=1.50 days squared

For both surgical procedure the length of time to recovery is normal random variable. Do the data provide sufficient sample evidence to indicate adifferencein the mean recovery time after surgical procedure I and mean recovery time after surgical procedure II? Test appropriate hypotheses. Use =0.05.

Assume thatpopulation variances may be assumed equaland common population variance is estimated with the value of pooled sample variance.

a. State null and research hypotheses about the difference in mean recovery times. ₀H:___________________ ₁H:___________________

Please help with this Practice Question.