RRB Group D 10-Dec-2018 Shift 1 Solved Paper

Question : 69 of 100

Marks: +1, -0

A and B together can complete a task in 1.8 days. However, if A works alone, completes half the job and leaves and then B works alone and completes the rest of the work, it takes 3.75 days in all to complete the work. If B is more efficient than A, how many days would it have taken B todo the work by herself?

3.0
3.3
2.25
2.7

Validate

Solution:

Suppose A work for x days the,

1/A×x=1/2

A=2x days

1/B(3.75-x)=1/2

B=2(3.75-x)=7.5-2x
A and B together can complete the work

{2x×(7.5-2x)}/{2x+7.5-2x}=1.8

x=2.25, 1.5

B will take= 7.5-2×2.25= 3 days

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