Question

A company has two types of machines, type R and type S. Operating at a constant rate, a machine of type R does a certain job in 36 hrs and a machine of type S does the same job in 18 hours. If the company used the same number of each type of machine to do the job in 2 hours, how many machines of type R were used?A. 3B. 4C. 6D. 9E. 12

Answer 1

Answer: C. 6

Explanation:

Given : Time taken by Machine R to do the job = 36 hours

Time taken by Machine S to do the job = 18 hours

Let x be the number of each type of machine to do the job.

Then , according to the question the required equation will be :-

`(x)/(36)+(x)/(18)=(1)/(2)\\\\\Rightarrow\ x((1)/(36)+(1)/(18))=(1)/(2)\\\\\Rightarrow\ (x)/(12)=(1)/(2)\\\\\Rightarrow\ x=(12)/(2)=6`

Hence, the number of machines of type R were used =6