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?
The LCM(25,30)=5*LCM(5,6)=150
So, after 150 minutes they will both have finished sets of papers.
...
To find the first time Riaz and Razi will finish marking a paper at the same time, we need to determine the least common multiple (LCM) of their marking times, which is the smallest time interval that is divisible by both 30 minutes and 25 minutes.
Step 1: Find the multiples of 30 and 25 until we find a common multiple.
Multiples of 30: 30, 60, 90, 120, 150, 180, 210, 240, 270, 300...
Multiples of 25: 25, 50, 75, 100, 125, 150, 175, 200, 225, 250, 275, 300...
Step 2: We can see that their first common multiple is 150 minutes.
Step 3: Convert the common multiple to the time format.
150 minutes is equal to 2 hours and 30 minutes.
Step 4: Add the common multiple to the starting time of 11:00 AM.
11:00 AM + 2 hours and 30 minutes = 1:30 PM.
Therefore, Riaz and Razi will finish marking a paper at the same time for the first time at 1:30 PM.