Question

In a school, the ratio of the number of pupils to the number of teachers is 20: 1. If the number of pupils is 840, how many teachers are there?

Answer 1

Answer:

good morning..........

Answer 2

Answer:

840=20

x = 1

by cross multiplying

20x=840

therefore x=42 hence, number of teachers are 42.

to make sure your answer is correct this is what to do:find the total ratio which is 20+1=21

so if total ratio = 21, then total number of pupils and teachers will be unknown so

21=x

20=840

by cross multiplying

20x=17640

x=882

this means total number of pupils and teachers are 882.

so now if total =882,and there are 840 pupils then the number of teachers will be=882-840

therefore number of teachers =42.