AlgebraVery hardClass size from two relations between boys and girls
Algebra practice question
In a class, the number of girls is 6 more than the number of boys. If the number of boys were doubled, there would be 4 more boys than girls. How many students are in the class?
Answer: 26
With b boys and g girls, g = b + 6 and 2b = g + 4. Substituting gives 2b = b + 10, so b = 10, g = 16, and the class has 26 students.
Common wrong answers
- If you answered 10
- 10 is the number of boys.
- If you answered 16
- 16 is the number of girls.
- If you answered 36
- 36 counts the doubled boys.
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