RRB Group D 19-Sep-2018 Shift 1 Solved Paper

Question : 74 of 100

Marks: +1, -0

A and B can complete a task together in 15 days, while A alone can complete it in 18.75 days. They start working together but A leaves 12.5 days before the completion of the work. For how many days did A and B work together?

10
11.25
13.75
12.5

Validate

Solution:

\;{1}/{ {B}} {x}+\;{1}/{ {A}}( {x}-12.5)=1

(\;{1}/{ {A}}+\;{1}/{ {B}}) {x}-\;{12.5}/{ {A}}=1

\;{x}/{15}-\;{12.5}/{18.75}=1

\;{x}/{15}=1+\;{2}/{3}

x=\;{5 × 15}/{3}=25

A and B together work for 25-12.5=12.5 days

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