IBPS Clerk Mains 2017 Paper

(c) 15 women can complete the work in ‘M’ days
1 woman can complete the work in ‘15M’ days ... (i)
21 child can complete the work in (M – 4) days
1 child can complete the work in 21(M – 4) days ... (ii)And also,
35 women can complete the work in ‘N’ days
1 woman can complete the work in ‘35N’ days ... (iii)
63 child can complete the work in ‘N – 4’ days
1 child can complete the work in 63(N – 4) days ... (iv)
Equate (i) & (iii) and (ii) & (iv)
15M=35N⇒

M

N

=

7

3

⇒N

3

7

M...(v)
21(M–4)=63(N–4)⇒M–4=3N–12
⇒ 3N – M = 8... (vi)
Using (v) and (vi)
3[

3

7

M]−M=8

9M−7M

7

=8
⇒M=

8×7

2

=28