The number of emails a friend receive each day during last 20 days is shown below. what number of days she receive 19 or fewer e-mails in a day?

a. 7

b. 11

c. 12

d. 15

To answer the problem just add the frequencies that correspond to email counts that are 19 or fewer. So you're adding the counts that correspond to 0-9 and 10-19. So the frequency of 0-9 is 4 and the frequency of 10 - 19 is 7. So 4 + 7 = 11