A classy ratio
There are six more girls than boys in Miss Spelling's class of 24 pupils. What is the ratio of girls to boys in the class?
Age
11 to 14
Challenge level
Problem
There are six more girls than boys in Miss Spelling's class of $24$ pupils. What is the ratio of girls to boys in the class?
If you liked this problem, here is an NRICH task that challenges you to use similar mathematical ideas.
Student Solutions
Answer: 5:3
Using numbers
24$\div$2 = 12, 12+3 and 12$-$3 are 6 apart and add up to 24
(or use pairs of numbers that add up to 24)
15 girls and 9 boys
Ratio 15:9 = 5:3
Using algebra
There are $g$ girls and $b$ boys:
$$g+b=24\\ \hspace{1mm} \\g=b+6\Rightarrow g-b=6$$
Adding the two equations gives $$2g = 30$$ So $g=15$, $b=9$ and $g:b=15:9=5:3$