You Are Looking at a Normal Distribution of IQ Scores

You are looking at a normal distribution of IQ scores. A friend thinks that the graph is really cool and wants to know between what two scores (above and below the mean) would about 50% of the people fall. You immediately say

A) 90 and 110
B) 85 and 115
C) 80 and 120
D) 80 and 100
E) you cannot tell from this graph