How Many Apps for Your Smartphone? A random sample of n=461 smartphone users in the US in January 2015 found that 355 of them have downloaded an app.¹ Of the n=355 smartphone users who had downloaded an app, the average number of apps downloaded was 19.7.

(a) Give notation for the parameter of interest.

(b) Give the notation for the quantity we use to make the estimate.

(c) Give the value of the best estimate. Enter the exact answer.