In Mr. Decker's class, the ratio of boys to girls is 3:7. The class sizes at Mr. Decker's school range from 22 to 34 students per class. What is the total number of students in Mr. Decker's class?
The ratio is 3:7.
Let's add the two parts of the ratio together.
This gives us 3 + 7 = 10
So, for every 10 pupils Mr. Decker has, 3 will be boys and 7 will be girls.
Since we are not allowed to deal with fractional pupils, Mr Decker's class must be an integer multiple of 10. i.e, 10, 20, 30, ...
All the classes in Mr. Decker's school range in size from 22 to 34.
The only integer of 10 in this range is 30.
Therefore, Mr. Decker has 30 pupils in his class, 9 boys and 21 girls