Yahoo Answers: Answers and Comments for It takes a man one hour to mow his lawn. It takes his son 90 minutes to mow the same lawn.? [Mathematics]
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From tinn
enUS
Wed, 19 Oct 2011 07:18:27 +0000
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Yahoo Answers: Answers and Comments for It takes a man one hour to mow his lawn. It takes his son 90 minutes to mow the same lawn.? [Mathematics]
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From DWRead: father's speed = 1 lawn/hour
son's sp...
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Wed, 19 Oct 2011 07:21:15 +0000
father's speed = 1 lawn/hour
son's speed = 1 lawn/1.5 hours = 2/3 lawn/hour
combined speed = (1+2/3) lawn/hour = 5/3 lawn/hour = 3/5 hour/lawn
3/5 hour × 60 minutes/hour = 36 minutes

From Como: Let`s be civilised and go metric !
Let area...
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Wed, 19 Oct 2011 07:25:55 +0000
Let`s be civilised and go metric !
Let area of lawn be X m ²
father`s rate of work = X / 60 m ² / min
son`s rate of work = X / 90 m ² / min
Combined rate = X/60 + X/90 m ² / min = 5X/180 m ² / min
Time for both working together is given by :
Area / rate = X / [ 5X/180 ] min = 180/5 min = 36 min

From jan vincent: rate multiplied by time equals work done
ra...
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Wed, 19 Oct 2011 07:25:25 +0000
rate multiplied by time equals work done
rate of father is 1/60
rate of sone is 1/90
together (1/60 + 1/90)
to solve for time
(1/60 + 1/90)(x) = 1 (since only one mow is lawned)
hence x= 5400 / 150
or basically 36 minutes

From Funnelweb: It will take 75 minutes because, guess what!, ...
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Wed, 19 Oct 2011 07:22:44 +0000
It will take 75 minutes because, guess what!, they only have one lawnmower!
So the man mows half the lawn in 30 minutes, then the son mows the other half of the lawn in 45 minutes: 30 + 45 = 75 minutes.

From Bryan: (60*90)/(60+90)= 36 mins
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Wed, 19 Oct 2011 07:21:26 +0000
(60*90)/(60+90)= 36 mins

From rhodaback: how plenty do they mow in a million hour Jack ...
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Thu, 08 Dec 2016 10:03:15 +0000
how plenty do they mow in a million hour Jack = a million/6 Marilyn = a million/3 time = x x/6 + x/3 = a million discover consumerfriendly denominator x/6 + 2x/6 = 6/6 x + 2x = 6 3x=6 divide by using 3 on the two ingredient x=2 they are going to take 2 hours to mow the backyard at the same time

From cantabrigian: It depends on whether they have more than one ...
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Wed, 19 Oct 2011 07:27:27 +0000
It depends on whether they have more than one lawnmower.

From Anonymous: time=1/ ((1/60)+(1/90))
= 36 minutes
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Wed, 19 Oct 2011 07:27:27 +0000
time=1/ ((1/60)+(1/90))
= 36 minutes

From Anonymous: 45 minutes.
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Wed, 19 Oct 2011 07:20:36 +0000
45 minutes.