Recitation 14

Inference about Population Proportions

1.

A newspaper reported the results of a survey of local residents to assess public opinion regarding duck hunting on a local lake. A sample of 750 residents included 560 who strinly opposed duck hunting on the lake.

(a)

Find a 90% confidence interval for the proportion of all local residents who oppose duck hunting on the lake.

(b)

Does this sample provide evidence to conclude thet the majority of local residents oppose duck hunting on the lake? Set up a test of significance of an appropriate pair of hypotheses, compute the p-value, and interpret the result.

2.

A study reported that 36 of 193 female bats in flight spent more than 5 minutes in the air before locating food. For maile bats, 64 out of 168 spent more than 5 minutes in the air.

(a)

Find a 95% confidence interval for the difference in the proportions of flights longer than 5 minutes for male and female bats?

(b)

Is there sufficient evidence to conclude that the proportion of flights longer than 5 minutes differs for male and female bats?