At a large university, data were collected on the number of sisters and brothers that each student had. Let the random variable x represent the number of sisters and the random variable y represent the number of brothers. The distribution of x has mean 1. 00 and standard deviation 0. 94. The distribution of y has mean 1. 07 and standard deviation 1. 4. What is the mean of the distribution of x+y ?.

Raul has one solution that is 20% acid by volume and one solution that is 50% acid by volume. he plans to mix together some of each solution to create 30 milliliters of a solution that is 40% acid by volume. how many milliliters of the 20% acid solution should raul use to create the 40% acid solution? can someone explain this to me? i know that the answer is 10 milliliters, but i don't know how to get it.