### Brain Teasers

# Car Wash

If Bob can wash a car in 8 minutes and Joe can wash a car in 12 minutes, how long would it take to wash the car together?

### Hint

If Bob can do it in 8 with no help, how must faster can he do it with help?### Answer

It would take 4 minutes and 48 seconds.In 1 minute Bob washes 1/8 of the car and Joe washes 1/12 of the car. This makes 3/24ths and 2/24ths of the car washed, or a total of 5/24ths. Therefore the number of minutes taken for a whole car is 24/5, or 4.8 minutes.

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