Latest GMAT Aptitude Question SOLUTION: A and B can complete work together in 5 days. If A works at twice his speed and B at half of his speed, this work can be finished in 4 days. How many days would it take for A alone

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(#M40165411) GMAT Numerical Ability question Math Keep an EYE

A and B can complete work together in 5 days. If A works at twice his speed and B at half of his speed, this work can be finished in 4 days. How many days would it take for A alone to complete the job?

Asked In GMAT Nouman (5 years ago)

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srishti  (4 years ago)

A one day work=1/x
B one day work=1/y

(A+B)=1/x+1/y=1/5
(x+y)/xy=1/5
5(x+y)=xy -------(1)

if A worked at twice =2/x
B worked at half=1/2y

2/x+1/2y=1/4
(4y+x)/2xy=1/4
8y+2x=xy-----(2)

substitute (2) in (1)

8y+2x=5x+5y
3y=3x

y=x that means number days worked by A alone is equal to B alone

substitute in (1)

1/x+1/x=1/5
2/x=1/5
A=10 days

B=10days

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Somjit Pramanick  (5 years ago)

ans: 1


x+y=5

2x+.5y=4 or 4x+y=8

4x+y-x-y=8-5=3 or 3x=3

=> x=1

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