Question

Q: An airport official wants to demonstrate that the P1 = proportion of delayed flights after a storm for Airline 1 is less than P2 = proportion of delayed flights after a storm for Airline 2. Random samples from two airlines after a storm showed that 51 out of 200 (.255) of Airline A’s flights were delayed, and 60 out of 200 (.30) of Airline B’s flights were delayed. What is the value of the test statistic?

A) z = -2.50

B) z = -1.50

C) z = -2.00

D) z = –1.00

Answer 1

p1 = 0.255, p2 = 0.30

n1 = n2 = 200

p = (p1*n1 + p2*n2)/(n1 + n2) = 0.2775

The value of the test statistic =

= -2.01

Thus, the required test statistic is z = -2.00