Answer
11 people
Work Step by Step
We can find this number by finding the sum of the heights of the bars that represent the number of people who have an average monthly balance of 301 to 400 dollars, 401 to 500 dollars and over 500 dollars.
The heights of these bars are 6, 2, and 3, respectively, so we know that $6+2+3=11$ people have an average monthly balance of 301 dollars or more.
