I did this problem but am not too sure it's right, have a look Of all households making less than $25,000 annually, 45% of them use coupons weekly when shopping for groceries. Suppose 10 households making less than $25,000 annually are selected at random. What is the variance of the number of households that use coupons weekly? I got 4.5 But I have no clue how to do this one, the book doesn't explain anything Suppose 30% of all M&Ms are brown. If 7 M&Ms are randomly selected, what is the probability that at most 1 is brown?