Carver Memorial Hospital's surgeons have a new procedure that they think will decrease the time to perform an appendectomy.A sample of 8 appendectomies using the old method had a mean of 38 minutes with a variance of 36 minutes,while a sample of 10 appendectomies using the experimental method had a mean of 29 minutes with a variance of 16 minutes.For a right-tail test of equal means (assume equal variances),the pooled variance is:
A) 14.76
B) 26.00
C) 24.75
D) 27.54

Question

Quizplus · Accepted Answer

To find the pooled variance, we use the formula:

pooled variance = ((n1-1)*s1^2 + (n2-1)*s2^2)/(n1+n2-2)

where n1 and n2 are the sample sizes, s1^2 and s2^2 are the variances of each sample.

Plugging in the values given, we have:

pooled variance = ((8-1)*36 + (10-1)*16)/(8+10-2)
               = (7*36 + 9*16)/16
               = 252/16 + 144/16
               = 24.75

Therefore, the answer is C) 24.75.

Carver Memorial Hospital's Surgeons Have a New Procedure That They