AlgebraEasy–MediumLeft-handed pupils in a class
Algebra practice question
In a class of 15 pupils, there are four times as many right-handed pupils as left-handed pupils. How many pupils are left-handed?
Answer: 3
r = 4l and r + l = 15 give 5l = 15, so l = 3.
Common wrong answers
- If you answered 5
- 5 divides 15 by 3 instead of by 5.
- If you answered 12
- 12 is the number of right-handed pupils.
- If you answered 3.75
- 3.75 divides 15 by 4, ignoring the left-handed pupils in the total.
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