372 notebooks are given out to 60 students of a class, 5 notebooks to each boy and 8 notebooks to each girl. How many boys are there in the class?
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → 36
If all 60 were boys, the total would be 60 × 5. Each of the girls gets 3 more, so the extra notebooks count the girls.
Total if all were boys \(=60\times5=300\)
Extra \(=372-300=72\)
Number of girls \(=72\div3=24\)
Number of boys \(=60-24=36\)
Check: \(36\times5+24\times8=180+192=372\)
There are 36 boys.
Why the other options are incorrect
Option (2) 24 — Incorrect. This is the number of girls, not of boys.
Option (3) 72 — Incorrect. This is the number of extra notebooks, 72; each of the girls gets only 3 extra, so it must be divided by 3.
Option (4) 9 — Incorrect. This divides the extra 72 notebooks by 8 instead of by the difference \(8-5=3\).