IBPS RRB Office Assistant 2020 Paper

According to the question,

1

A

+

1

B

=

1

20

...(i)

1

B

+

1

C

=

1

30

... (ii)
and

1

C

+

1

A

=

1

40

... (iii)
On adding Eqs. (i), (ii) and (iii), we get
2(

1

A

+

1

B

+

1

C

)=

1

20

+

1

30

+

1

40

⇒

1

A

+

1

B

+

1

C

=

13

240

... (iv)
On subtracting Eq. (ii) from Eq. (iv), we get

1

A

=

13

240

−

1

30

=

5

240

=

1

48

A = 48 days
∴ Now, on subtracting Eq. (i) from Eq. (iv), we get

1

C

=

13

240

−

1

20

=

1

240

∴ C = 240 days
Required ratio = 48 : 240 = 1: 5