EXAMPLE 3.1.3

The graph below shows the percentage distribution of grades on an exam.

Assuming that 828 people took the test, how many received grades of A or B?

EXAMPLE 3.1.3 SOLUTION

The graph will tell us what percentage of the students received grades of "A" or "B." Since 25% received a grade of "B" and 12% received a grade of "A," and nobody received more than one grade, the percent who received "A" or "B" is 21% + 25% = 46%.

To find the number of students who received grades of "A" or "B" we need to find 46% of 828. We do this by writing 46% as an equivalent decimal number, and then multiplying that decimal number by 828.

To convert 46% to an equivalent decimal number, we move the decimal point two positions to the left, and drop the "%" sign.

46% = 46.0% = .46

Now we multiply this number by 828.

.46(828) = 380.88, or 381 students if we round to the nearest whole number.