How do I calculate the frequency?

During one shift, the express lane clerk recorded how many times customers violated the "1 rule for his lane. In particular, he recorded how many items over the limit each violator pla conveyor belt. This data is summarized in the histogram below. NOTE: The last class actuall or more items," not just 7 items. 12 Frequency 0.5 1.5 2.5 3.5 4.5 5.5 6.5 7.5 # items over 10 What is the frequency of times the limit was exceeded by at most 3 items