Question

A girl scout troop sold cookies to raise funds. Each troop member recorded the number of boxes she sold. The number of boxes sold was normally distributed with a mean of 22 boxes sold and a standard deviation of 4 boxes. In order to help determine how many boxes would be sold the next year, the troop leader decided to focus on the range made from the bottom 30% to the top 20%. Find the number of boxes that represent the desired range values.

22 and 26
20 and 25
22 and 24
21 and 24

I think it's C but I have no real idea how to do this so if someone could explain I'd appreciate it.

Answer 1

So, if you have no idea, why do you think it's C?
You can play around with Z table stuff at

http://davidmlane.com/hyperstat/z_table.html

Answer 2

Because I'm supposed to make a guess so I made one...

But I really don't know how to do it, or what a z table is but ok.

Answer 3

its 20-25