If Hannah gives her younger sister 3 shirts, it does not matter what order she hands them to her. No matter the order, it will still be the same group of 3 shirt. Since order is not important this problem can be solved using a combination. Specifically, we are asked to find 8C3 (sometimes called "8 choose 3"). This is a fraction. In the numerator, we start with 8 and count down 3 numbers. In the denominator, we start with 3 and count all the way down to 1. your answer is 56
She should randomly select campers period, because she wants to estimate the percentage of "campers that ride once a week" and not for example what percentage of campers who ride that ride once a week...
