Boys and girls are in the ratio 7:8. After a 20% increase in boys and 10% increase in girls, what is the new ratio?

Problem restatement
Apply percentage increases to both parts of a ratio and simplify.

Given data

• Initial ratio Boys:Girls = 7:8
• Boys increase by 20%; Girls by 10%

Concept/Approach
Multiply each term by its respective growth factor, then reduce the resulting ratio.

Step-by-step calculation
New boys = 7 × 1.2 = 8.4New girls = 8 × 1.1 = 8.8New ratio = 8.4 : 8.8 = divide by 0.4 ⇒ 21 : 22

Common pitfalls
Adding percentages to the ratio numbers instead of applying multiplicative factors.

Final Answer
21 : 22