Question 285091

let us assume draining of the pool as 1 job

one drains in 12 hours 

so it completes 1/12 of the job in 1 hour

Second drains in 8 hours

so it compltes 1/8 job in 1 hour

third drains in 6 hours 

so it does 1/6 of job in 1 hour

In 1 hour all the three will do 1/12 +1/8 +1/6 in 1 hour

= 2+3+4 /24 

=9/24 job is done in 1 hour


1 job will be done in 24/9 hours = 2.66 hour or 2 hours & 40 minutes