In an on-line survey, a school learns that 77 of 100 parents prefer to receive the newsletter electronically. How many paper newsletters would the school estimate
are needed if there are 650 parents?

77% of the school want electronic newsletters, so 23% of the school want physical paper newsletters.

77% of 650 is 500.5.
23% of 650 is 149.5.

650/100 = 6.5
6.5x77 = 500.5
6.5x23 = 149.5

It's best to round that figure up to 150 as there will not be a parent who only needs half of the newsletter.