I am doing a midterm review and would very much like to know how to solve these questions

1. Millions of people now shop online. According to recent studies 77% of people purchase items online,

A) What is the probability that in a random sample of 200 people, between 75% and 80% purchased items online?

B) Many of these online are sold at a cheaper cost as an incentive for buying online. In a random sample of 200 shoppers, 170 had purchased something online. What is the probability that in the random sample, 170 or more would have purchased something online?

C) Using the sample data, find a 98% confidence interval for the true mean proportion of shoppers that now purchase items online.

D) What sample size is needed to estimate the true proportion of shoppers buying items online withing + or - 2% points?

E) What assumptions do we make about the sampling distribution of the sample proportion?