Libraries. A library conducted a survey in order to better know its customers and to better market its services.

The survey found that 354 of 592 surveyed single adults had current library cards. 1243 of 1587 married adults had library cards.

a) Is there evidence that the percentage of adults with library cards is different between single and married adults?

b) Give a 99% confidence interval for the difference.

c) Do you think the difference should affect how a library markets its services?