Question

Ramayana can finish the work in 12hrs and Mohan can finish the work in 15hrs if both complete together how much time need to finish the work ​

Answer 1

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Mohan does (1/8)th of the work in one hour while Sundar does (1/10)th in the same hour.

Let the work get completed in x hours with both Mohan and Sundar working together. Mohan worked for (x-1) hours while Sundar worked for all the x hours.

So, we have (x-1)/8 + x/10 = 1. Or

10(x-1) + 8x = 80

10x+8x = 80+10

18x = 90

x = 5.

So Mohan worked for 4 hours while Sundar worked for 5 hours. Answer.

Check: (4/8) +(5/10) = (1/2)+(1/2) = 1. Correct.

Answer 2

Answer:

Time taken by Ramayana= 12 hrs

One hour work of Ramayana=1/12

Time taken by Mohan= 15 hrs

One hour work of Mohan=1/15

Time taken by both when they work together=

1/12+1/15=

5+4/60=9/60

3/20

Therefore, work done by both together=20/3hrs=6.67 hrs.