Using the 68-95-99.7 rule:

Question

Assume that a set of test scores is normally distributed with a mean of 100 and a standard deviation of 20. Use the 68-95-99.7 rule to find the following quantities:
Suggest you make a drawing and label first…
a. Percentage of scores less than 100 =
b. Relative frequency of scores less than 120 =
c. Percentage of scores less than 140 =
d. Percentage of scores less than 80 =
e. Relative frequency of scores less than 60 = 32
f. Percentage of scores greater than 120 =

Answer 1

We cannot make a drawing here. But from Google:

http://en.wikipedia.org/wiki/68-95-99.7_rule

In the future, you can find the information you desire more quickly, if you use appropriate key words to do your own search. Also see http://hanlib.sou.edu/searchtools/.