Question

PLEASE ANSWER THIS QUESTION

A and B together can do a work in 20 days, B and C in 40 days, and A and C in 30 days. Who is the most efficient among the three persons?

BRAINLIEST QUESTION

Answer 1

A is the most efficient among the three persons.

Answer 2

A and B can do a work in 20 days.

(A + B)'s one day work = 1/20 ------(1)



B and C can do a work in 40 days.

( B +C)'s one day work = 1/40 -----(2)


C and A can do a work in 30 days.

( A + C)'s one day work = 1/30 -----(3)


On adding equation 1, 2 and 3, we get

( A + B + B + C + C + A) = 1/20 + 1/40 + 1/30

=> 2 ( A + B + C) = ( 6 + 3 + 4) / 120

=> A + B + C = 13 / 240 ------(4)

On subtracting equation 1 from 4, we get

C' s one day work = 13 / 240 - 1 /20

= ( 13 - 12) / 240

= 1/240

C can do the work alone in 240 days.

Now,

On subtracting equation 2 from 4, we get

A's one day work = 13 /240 - 1 /40

= ( 13 - 6) / 240

= 7 / 240

A can do the work in 240/7 = 34.29 days

Now,

On subtracting equation 3 from 4, we get

B's one day work = 13/240 - 1/30

= ( 13 - 8) / 240

= 5 / 240

= 1 / 48

B can do the work in 48 days.

So,


The most efficient is A