Of the 15-year-olds at a karate school, 9 have black belts and 15 have brown belts. Among the 16-year-olds, 17 have black belts and 19 have brown belts. Which age group has a higher ratio of black belts to brown belts?

The ratio of black belts to brown belts:

Among 15-year-olds - 9 : 15

Among 16-year-olds - 17 : 19

We have to find which is higher:

 We can compare the ratios more easily by expressing them in percentage.

To convert into %, multiply the ratio by 100.

Thus,

And

Comparing, we get

60% < 89.47%

Thus, the 16-year-olds have a higher ratio of black belts to brown belts.