The data set in the accompanying table contains last month's credit card purchases of 100 customers randomly chosen from a segment of a major credit card issuer. The marketing department is considering a special offer for customers who spend more than $1000 per month on their card. From these data construct a 90% confidence interval for the proportion of customers in this segment who will qualify.

What is the 90% confidence interval? Please show all work. It would help me understand the process better.

See data below:

The interval is not 9.3% to 20.7% (after rounding). I got that wrong