# Thread: Inference for Proportions (AP Stats)

1. ## Inference for Proportions (AP Stats)

A can of pumpkin pie mix contains a mean of 30 ounces and a standard deviation of 2 ounces. The contents of the cans are normally distributed. What is the probability that four randomly selected cans of pumpkin pie mix contain a total of more than 126 ounces?
We haven't really done anything like this in class (or I don't remember it..). Can anyone explain the procedure at least? I would solve it myself if I knew how.

Thanks.

2. Originally Posted by WhoCares357
We haven't really done anything like this in class (or I don't remember it..). Can anyone explain the procedure at least? I would solve it myself if I knew how.

Thanks.
The sum of n independent normal random variables is also a normal random variable: Sum of normally distributed random variables - Wikipedia, the free encyclopedia

In your case the mean is 4 (30) = 120 and the variance is 4 (2^2) = 16 => sd = 4.

3. Originally Posted by mr fantastic
The sum of n independent normal random variables is also a normal random variable: Sum of normally distributed random variables - Wikipedia, the free encyclopedia

In your case the mean is 4 (30) = 120 and the variance is 4 (2^2) = 16 => sd = 4.
Thank you .