A sample of size 150 from population 1 has 40 successes. A sample of size 250 from population 2 has 30 successes.

A sample of size 150 from population 1 has 40 successes. A sample of size 250 from population 2 has 30 successes. The value of the test statistic for testing the hypothesis that the proportion of successes in population 1 exceeds the proportion of successes in population 2 by 0.05 is:

A.

1.645.

B.

2.327.

C.

1.960.

D.

1.977.

why it is b