Question

Coronary bypass surgery: A healthcare research agency reported that 43% of people who had coronary bypass surgery in 2008 were over the age of 65. Fourteen coronary bypass patients are sampled.

(a) What is the mean number of people over the age of 65 in a sample of 14 coronary bypass patients? Round the answer to two decimal places.

The mean number of people over the age of 65 is BLANK

(b) What is the standard deviation of the number of people over the age of 65 in a sample of 14 coronary bypass patients? Round the answer to four decimal places.

The standard deviation of the number of people over age 65 is BLANK

Answer 1

We have

p = proportion of people who had coronary bypass surgery in 2008 were over the age of 65

p = 0.43

n = number of patients sampled = 14

a) mean  

= n*p

= 14*0.43 = 6.02

The mean number of people over the age of 65 is 6.02

b) the standard deviation = sqrt( n *p *(1-p))

= sqrt( 14*0.43*0.57)

   = 1.8524

The standard deviation of the number of people over age 65 is 1.8524