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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Comments
I disagree with your answer. It would take 4minutes and 48 seconds. Here`s why:- In 1 minute one washes 1/8 of a car and the other 1/12 of a car, i.e. 3/24ths and 2/24ths, or a total of 5/24ths. Therefore the number of minutes taken for a whole car is 24/5, or 4.8 minutes.
i do agree its 4.8 mins
Nov 22, 2001
I also have to disagree the job takes just under 5 mins (Oops cannot find my calculation)
i got the same answer as you guys
0.8 of a minute is 0.8 x 60 seconds = 48 seconds. See we all agree!
Thank You Little Big League! I knew how to do that one!
I have a suggestion to the editors.Once they have corrected the answer or teaser after the comments, they should remove the comments which pointed the mistakes.It creates confusion for those reading the teaser and comments later.As in this case, the answer is now correctly shown as 4 min 48 sec and comments disagree with the answer saying correct answer is 4.8 min or 4 min 48 sec. so it is confusing for later readers
Editting the comment isn't very workable, but including the date of the correction might help.
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