Mayank can do 50% more work than Shishu in the same time. Shishu alone...
Shishu alone does the work in 30 hours
So in 1 hour he does 1/30 of the work
Mayank in 1 hour does 1/30 + 1/2*1/30= 1/30 +1/60 = 3/60 = 1/20 of the work
Together in 1 hour they do 1/30 +1/20 = 5/60 = 1/12 of the work
Together they can finish the work in 12 hours
Shishu in 12 hours does 12/ 30 = 2/5
Remaining work = 3/5
3/5 X 12 = 36/5 = 7.2 hours
View all questions of this testMayank can do 50% more work than Shishu in the same time. Shishu alone...
Answer is 10.8 hrs , which is not there in options . how 7.2 can be the answer please explain ??
Mayank can do 50% more work than Shishu in the same time. Shishu alone...
Given information:
- Mayank can do 50% more work than Shishu in the same time.
- Shishu alone can do a piece of work in 30 hours.
- Shishu started working and had already worked for 12 hours when Mayank joined him.
To find:
- How many hours should Shishu and Mayank work together to complete the remaining work?
Solution:
Let's first find out how much work Shishu can do in 1 hour.
Shishu can do a piece of work in 30 hours.
Therefore, in 1 hour, Shishu can do 1/30th of the work.
Let's now find out how much work Mayank can do in 1 hour.
Mayank can do 50% more work than Shishu in the same time.
This means Mayank can do (1 + 50/100) = 1.5 times the work that Shishu can do in the same time.
Therefore, in 1 hour, Mayank can do 1.5/30th = 1/20th of the work.
Let's say the total work is 'L'.
Shishu has already worked for 12 hours.
Therefore, the remaining work is (L - (1/30 x 12)) = (29/30)L.
Shishu and Mayank need to work together to complete this remaining work.
Let's say they work together for 'x' hours to complete the remaining work.
In 'x' hours, Shishu can do (1/30 x x) = x/30th of the remaining work.
In 'x' hours, Mayank can do (1/20 x x) = x/20th of the remaining work.
Together, in 'x' hours, they can do [(x/30) + (x/20)] = (5x/60) = (x/12)th of the remaining work.
We need to find out the value of 'x' for which (x/12)th of the remaining work is equal to (29/30)L - (L/2).
[(x/12)L] = [(29/30)L - (L/2)]
[(x/12)L] = [(7/15)L]
x = (7/15) x 12
x = 7.2
Therefore, Shishu and Mayank need to work together for 7.2 hours to complete the remaining work.
Answer: Option (D) 7.2