RRB RPF RPSF SI and CONS Model Papers 9 with solutions

Question : 47 of 120

Marks: +1, -0

A and B can do a job in 6 and 12 days respectively. They began the work together but A leaves after 3 days. Then the total number of days needed for the completion of the work is :

Validate

Solution:

(3) A’s one day’s work =

1/6

B’s one day’s work =

1/12

(A + B)’s one day’s work

= 1/6+1/12={2+1}/12=1/4

(A + B)’s three day’s work

=3/4

Remaining work

= 1-3/4=1/4

∴ Required number of days

1/4×12/1+3

= 3 + 3 days = 6 days

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