RRB JE Maths Important Solved MCQs


A and B can complete a work in 15 days and 10 days respectively. They started doing the work together but after 2 days B had to leave and A alone completed the remaining work. The whole work was completed in :

A.

8 days

B.

10 days

C.

12 days

D.

15 days

Answer: Option C

 

 

(A + B)'s 1 day's work =

(

1

+

1

)

=

1

.

15

10

6

 

Work done by A and B in 2 days =

(

1

x 2

)

=

1

.

6

3

 

Remaining work =

(

1 -

1

)

=

2

.

3

3

 

Now,

1

work is done by A in 1 day.

15

 

Therefore

2

work will be done by a in

(

15 x

2

)

= 10 days.

3

3

Hence, the total time taken = (10 + 2) = 12 days.