If is a random variable with a mean of and standard deviation of , what is the mean and standard deviation of ?

An experiment is conducted on the watermelons that were grown on a small farm. They want to compare the average weight of the melons grown this year to the average weight of last year's melons. Find the mean of this year's watermelons using the following weights:

If you have ten independent random variables , normally distributed with mean and variance , what is the distribution of the average of the random variables,

Suppose you have three independent normally distributed random variables, , such that

has mean and variance ,

has mean and variance ,

has mean and variance .

What is the probability that the sum, , is less than ?