I am looking at this question and I am still confused after reading the accepted answer.
This is the question:
A company ships gift baskets that contain apples and pears. The distributions of weight for the apples, the pears, and the baskets are each approximately normal. The mean and standard deviation for each distribution is shown in the table below. The weights of the items are assumed to be independent.
Apples: Mean=4.72 oz, sigma=0.2 oz
Pears: Mean=5.41 oz, sigma=0.18 oz
Basket: Mean=13.52 oz, sigma=1.88 oz
Let the random variable W represent the total weight of 4 apples, 6 pears, and 1 basket. Which of the following is closest to the standard deviation of W?
(A) 1.90 ounces
(B) 1.97 ounces
(C) 2.26 ounces
(D) 3.76 ounces
(E) 3.83 ounces
Specifically, I was looking at these notes:
It's basically the same question but the method that the questioner used in the hyperlinked question is the same method used in these notes I found.