Answer:
a.) First check on the height of the bar that ranges between 20 and 24 which is 6. The 6 is the number of students who bought 20 books or more, so get the percentage of those students who bought 20 or more books; divide 6 which is the number of students who bought 20 books or more with the total number of students which is 40 then multiply with 100.
% of students who bought 20 or more books = 6/40 ×100
=15
Step-by-step explanation:
b.) Find the area of a trapezium
= 1/2 × {a+b} × h
= 1/2 × {9 + 13} ×12
= 132
= 1/2 × {13 + 6} × 12
= 108
Mean no. of books bought = 132 + 108
= 240