Question

Mohan can repair an Instrument in 40 hours. Ram can repair the same instrument in 30 hours. Mohan and Ram work together to repair the same instrument for 8 hours. Then, Mohan goes away. The number of hours that Ram takes to complete the work is (in hours)
1. 16
2. 15
3. 14
4. 10

Answer 1

Correct Answer - Option 1 : 16

Given:

Time is taken by Mohan = 40 hours

Times is taken by Ram = 30 hours 

Time is taken by Ram and Mohan for work together  = 8 hours

Formula used:

The efficiency of A = Total Work/Time is taken by A

The efficiency of B = Total Work/Time is taken by B

Calculation:

Let total work be 120 units [LCM of (40, 30)]

The efficiency of Mohan= 120/40 = 3

The efficiency of Ram = 120/30 = 4

The total efficiency of Mohan and Ram = 3 + 4 = 7

Mohan and Ram Work together for 8 hours = 8 × 7 = 56 units 

Remaining work which is done by Ram = 120 - 56 = 64 units 

Times is taken by Ram to do remaining work = 64/4 = 16 hours

∴ The time is taken by Ram to do the remaining work is 16 hours.