Question

Last year at a certain high school, there were 50 boys on the honor roll and 120 girls on the honor roll. This year, the number of boys on the honor roll increased by 22% and the number of girls on the honor roll increased by 15%. By what percentage did the total number of students on the honor roll increase? Round your answer to the nearest tenth (if necessary).

Answer 1

Explanation:

50 boys increased by 22%.

that means the number 50 is multiplied by 1.22 (= 1 + 0.22), as 22% = 0.22 :

50 × 1.22 = 61

the difference is 61 - 50 = 11

120 girls increased by 15% :

120 × 1.15 = 138

the difference is 138 - 120 = 18

the total number of additional honor roll students is

11 + 18 = 29

the total number of students was originally

50 + 120 = 170 = 100%

1% = 100%/100 = 170/100 = 1.7

how many % are the 29 difference ?

as many % as times that 1% fit into 29 :

29 / 1.7 = 17.05882353... ≈ 17.1%

so, the number of honor roll students increased by about 17.1%.