Question

Sally can detail a car in 50 minutes. Manny does the same job in 35 minutes. How long will it take them to detail a car together

Answer 1

27 minutes, and 16 seconds

Answer 2

Sally and Manny together can detail a car in 20 minutes 59 seconds

SOLUTION:

Given,

Sally can detail a car in 50 minutes

Work done by sally in one minute =
`(1)/(50)`

Manny does the same job in 35 minutes

Work done by Manny in one minute =
`(1)/(35)`

Now, work done by Sally and Manny together in one minute =
`(1)/(50)+(1)/(35)`

`=(1)/(5)\left((1)/(10)+(1)/(7)\right)`

`=(1)/(5)\left((7+10)/(7 * 10)\right)`

`=(1)/(5) * (17)/(70)`

`=(17)/(350)`

So, the time taken to detail a car by sally and manny together is
`(350)/(17)=20.5882`

Hence, sally and manny together can detail a car in 20 minutes 59 seconds or 23 minutes(approximately)