For each exercise, perform these steps. Assume that all variables are normally or approximately normally distributed.

a. State the hypotheses and identify the claim.
b. Find the critical value(s).
c. Compute the test value.
d. Make the decision.
e. Summarize the results.
Use the traditional method of hypothesis testing unless otherwise specified.

In 2010, 91% of households had at least one cell phone. A random sample of 300 households in each of two different counties indicated the following. At the 0.01 level of significance, can it be concluded that a difference in proportions exists?

County X County Y n 300 300 X 255 278