mean and variance

7) suppose the average weight of an item labeled 16 ounces actually has mean17 ounces and variance4 (ounce^2). What is the approximate probabilitythat the combined weight of 25 items exceeds 445 ounces? What theorem is useful in answering this question?

This is a standard normal distribution theorem question
E(X)=17 and Var(X)=4
Then 25X is also a normal …

This shows how to find the probability that a weight is in a certain range given mean and variance.