Question

A can do 1 by 2 of a piece of work in 5 days. B can do 3 by 5 of the same work in 9 days and C can do 2 by 3 of that work in 8 days. In how many days can three of them, together do the work?<br />(1) 3 days (2) 5 days (3) 9 by 2 days (4) 4 days​

Answer 1

Answer:

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ATQ,

A can do 1/2 of the work in 5 days

=> A can do the whole work in 5 × 2/1 = 10 days

B can do 3/5 of the work in 9 days

=> B can do the whole work in 9 × 5/3 = 12 days

C can do 2/3 of that work in 8 days

=> C can do the whole work in 8 × 3/2 days = 12 days.

Therefore, ( A + B + C)’s 1 days’ work

= 1/10 + 1/15 + 1/12

$= \frac{6 + 4 + 5}{60} = \frac{15}{60} = \frac{1}{4}$

Hence, A + B + C can complete the whole work in 4 days.