Question

-.A,B, and C together complete
a work in 2 days. If A and B
need 2.4 days to complete the
work, while B and C together
complete the work in 4 days
then in how many days will B
alone do the work?
(1) 9
(2) 5
(3) 4.4 (4) 6​

Answer 1

(1/A) + (1/B) + (1/C) = (1/2) ——> 1

(1/A) + (1/B) = (1/2.4) = (5/12) ——> 2

(1/B) + (1/C) = (1/4) ——> 3

Adding equations 2 & 3,

(1/A) + (1/B) + (1/B) + (1/C) = (5/12) + (1/4)

(1/A) + (1/B) + (1/C) + (1/B) = (8/12) = (2/3)

(1/2) + (1/B) = (2/3) [From 1]

(1/B) = (2/3) - (1/2)

(1/B) = (1/6)

There B takes 6 days to complete work.

Answer: Option 4