11.44 Doctors are interested in the relationship between the dosage of a medicine and the time required for a patient’s recovery. The following table shows, for a sample of 10 patients, dosage levels (in grams) and recovery times (in hours). These patients have similar characteristics except for medicine dosages.

Dosage level 1.2 1.3 1.0 1.4 1.5 1.8 1.2 1.3 1.4 1.3 Recovery time 25 28 40 38 10 9 27 30 16 18

a. Estimate the linear regression of recovery time on dosage level.

b. Find and interpret a 90% confidence interval for the slope of the population regression line.

c. Would the sample regression derived in part a be useful in predicting recovery time for a patient given 2.5 grams of this drug? Explain your answer.