Question

1 )A. B & C together can complete a piece of work in 10
days, all the three started working at it together
& after 4 days 'A' left, then B&C together completed
the work in 10 more days 'A' alone can complete the work is
a)15 days
b)16 days
c) 25 days
d) 26 days
​

Answer 1

Answer:

25 days......................

Answer 2

Let the total work be ' 1 '

A + B + C = 10 days.

=> A + B + C 's 1 day work = 1 / 10.

A + B + C 's 4 days work = 4 / 10.

☞ Remaining work = 1 - 2 / 5 [ LCM = 5 ]

=> ( 1 × 5 / 1 × 5 ) - ( 2 × 1 / 5 × 1 )

=> 5 - 2 / 5

=> 3 / 5.

☞ so, 3 / 5 of the work done by ( B + C )

=> ( B + C ) = 3 / 5 = 10 days.

=> ( 10 / 3 ) / 5

=> 3 / 5 × 10

=> 3 / 50 days.

☞ A alone work,

=> ( A + B + C 's work ) - ( B + C 's work)

=> 1 / 10 - 3 / 50 [ LCM = 50 ]

=> ( 1 × 5 / 10 × 5 ) - ( 3 × 1 / 50 × 1 )

=> 5 - 3 / 50

=> 2 / 50

=> 1 / 25.

• A alone can complete the work in 25 days.