A recent survey showed that from a sample of 500 packages delivered by a Postal Service, 480 were delivered on time. a) Construct a 95% confidence interval for the proportion of all packages that are...

A recent survey showed that from a sample of 500 packages delivered by a Postal Service, 480 were delivered on time.

1. a) Construct a 95% confidence interval for the proportion of all packages that are delivered on time by the Postal Service.


2. b) The manager of the Postal Services claims that 98 percent of their mails are delivered on time. Test at the 1% significance level to determine whether the true proportion is less than 98 percent.