The numbers of cookies in a shipment of bags are normally distributed, with a mean of 64 and a standard deviation of 4. What percent of bags of cookies will contain between 60 and 68 cookies?
* 50%
* 13.5%
* 68%
* 34%
C. 68%
I recommend
http://davidmlane.com/hyperstat/z_table.html
for you last two questions