Hi,

I have a problem regarding CLT:

"The lengths of mass produced nails are normally distributed with a mean of and variance of . 16 nails are randomly chosen and laid end to end.

What is the probability that its length exceeds 48.5cm?"

This is my working out, I'm not sure what i am doing wrong:

Let , where are identically and independently distributed variables.

So, each of ~

Thus, ~

We need to find . So

Then, I'm stuck here. Any help will be greatly appreciated thanks