Question

It takes Riaz 30 minutes to mark a paper, Razi only takes 25 minutes to mark a paper, if
they both start marking a paper at 11:00 AM, what is the first time they will finish marking
a paper at same time?

A) 12:30
B) 12:45
C) 1:00
D) 1:30
E) 12:25

Answer 1

At 12:30 they both will finish marking.

Answer 2

There’s a simple way to get this.

How I calculated this:

For Riaz, count up a few times of times he has finished a paper.

30 minutes, 60, 90, 120, 150.

For Razi do the same.

25, 50, 75, 100, 125, 150 minutes.

Notice how It’s both 150 minutes for a certain paper?

Convert the 150 minutes to hours.

60 minutes in an hour, so that would be 2 hours and 30 minutes.

They started marking at 11:00 AM, therefore they will finish a paper at the same time on 1:30 PM. The answer is D.