10-A 13. Can someone show me how to do this problem?

Will rate a thumb up for good response thanks so much (PLEASE CIRCLE OR HIGHLIGHT final answer thx)

Supervisor Kenneth Peterson wants to determine the percent of time a machine in his area is idle. He decides to use work sampling, and his initial estimate is that the machine is idle 20% of the time. (Round all intermediate calculations to at least two decimal places before proceeding with further calculations.) The number of observations that need to be taken by Peterson to be 98.00% confident that the results will be less than 5% from the true result = (round your response to the immediate higher whole number)