S.O.S. Mathematics CyberBoard

Nine 16 to 24-year olds are chosen at random and the number who spend time on the internet within one standard deviation

of the mean is modelled by the random variable X.

Assume independence, find P (X is greater than or equal to 5)

The time, T, spent on the internet by 16 to 24-year-olds in hours per week is modelled by a normal distribution with mean 30 and variance 64.

I am unclear on how to interpret this question.

My questions are:

How are the random variables X and T related to each other when doing the calculation?

How is the “within one standard deviation” reference used for the calculation? Is this a sampling mean distribution, and if so, is the

“one standard deviation” referring to the standard error?

Just a quick explanation ought to be sufficient to get me started.

Thanks in advance.

It's fine. I can do this question now.