Shift workers at Yadey Consulting like to use the office phone to make long distance calls. The length of the last 40 long distance calls made from the office phone was recorded and displayed in the percent ogive below. Percent of calls less than upper limits are shown on the graph.

a.What percent of the calls lasted less than 15 minutes?

%

b.What percent of the calls lasted between 10 and 20 minutes?

%

c.How many of the calls lasted less than 10 minutes?

d.How many of the calls lasted at least 20 minutes?