Topic: How much do you know maths 3?

A man fills a tank in 30mins. A second man fills the same tank in 40mins. And a third man fills it in 60mins. If the three of them fill the tank together:-

i) how long will it take to completely fill the tank?

ii) how long will it take to fill the tank if the third man quits after the tank is 1/4 filled?

The first correct answer gets an automatic employment with Total lol - Just Kidding. But guys try to solve this question.

let first man be A
Second man be B
and third man be C
A=1tank=30mins
B=1tank=40mins
C=1tank=60mins

A completes 1/30tank in 1min
B completes 1/40tank in 1min
C complete 1/60tank in 1min

A,B and C complete (1/30 + 1/40 + 1/60)of Tank in 1min
(1/30 + 1/40 + 1/60)= 9/120= 3/40 of Tank in 1min
it will take A,B and C man 1min to fill 3/40 of Tank
it will take 1min * 40/3 to Fill 1 tank
it will take them 13.3mins to fill 1 Tank

b)from above it takes 3.3min for the tank to get to 1/4th filled.
in 3.3mins A will have filled (1/30 * 3.3) of Tank
in 3.3mins B will have filled (1/40 * 3.3) of Tank
and in 3.3mins C will have filled (1/60 * 3.3) of Tank
i.e A=0.11of Tank, B= 0.0825 of Tank and C= 0.055 of Tank.
all men working together in 3.3mins would have completed 0.11 + 0.0825 + 0.055=0.2475 of tank
1-0.2475=0.7525 of tank is left to be filled.
A& B fill rate is 1/30+1/40=7/120 of tank/min
A&B fill rate = 0.0583 of tank/min
recall the vol. left to fill is 0.7525
the time it will take A&B is (0.7525/0.0583) to fill the left vol.
=12.9mins
in all, it takes 3.3+12.9=16.2 to fill the tank.