Phone A recent study shows that 17% of a random sample of 1954 cell phone owners do most of their online browsing on their phone. The standard error for the proportion is 0.0085. The sample size is large enough to use a normal distribution.

(a) Find and interpret a 90% confidence interval for the proportion of cell phone owners who do most of their online browsing on their phone.
(b) Use a normal distribution to test whether there is evidence that the proportion is greater than 0.15. Give all details of the test.