In a classroom, the ratio of students to teachers is 10:1. If there are 120 students, how many teachers are there?

easy 1 mark Class 6 · Mathematics · Ratio and Proportion

Answer

The correct answer is 12 — Thus there are 12 teachers.

Step-by-step solution

Let the number of teachers be $x$ .
The ratio 10:1 means there are 10 students for every 1 teacher, so students = $10 x$ .
Set $10 x = 120$ .
Solve for $x$ : $x = 120 d i v 10 = 12$ .
Thus there are 12 teachers.

Common mistake: confusing the order of the ratio and dividing students by 10 instead of multiplying.

Concept tested: ratio of two quantities