RRB JE Maths Important Solved MCQs

A and B can do a work in 8 days, B and C can do the same work in 12 days. A, B and C together can finish it in 6 days. A and C together will do it in :

A.

4 days

B.

6 days

C.

8 days

D.

12 days

Answer: Option C

 

 

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

1

;

6

 

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

1

;

8

 

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

1

.

12

 

Therefore (A + C)'s 1 day's work

=

(

2 x

1

)

-

(

1

+

1

)

6

8

12

 

=

(

1

-

5

(

3

24

 

=

3

24

 

=

1

.

8

So, A and C together will do the work in 8 days.