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Work Problem

by ssraf » Thu Jun 12, 2008 4:20 pm
A farm used 2 harvesting machines, H and K to harvest 100 acres of wheat. Harvesting machine H, working alone at its constant rate harvested 40 acres in 8 hours. K was brought in thereafter, and H and K working togethor at their respective rates harvested the remaining acres in 5 hours. How many acres per hour did K harvest?

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Re: Work Problem

by durgesh79 » Thu Jun 12, 2008 8:50 pm
ssraf wrote:A farm used 2 harvesting machines, H and K to harvest 100 acres of wheat. Harvesting machine H, working alone at its constant rate harvested 40 acres in 8 hours. K was brought in thereafter, and H and K working togethor at their respective rates harvested the remaining acres in 5 hours. How many acres per hour did K harvest?

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H's one hour work = 40/8 = 5
H and K together one hour work = 60/5 = 12
K's one hour work = 12 - 5 = 7

Option A
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by beeparoo » Thu Jun 12, 2008 8:50 pm
Rate(H & K) = Rate(H) + Rate(K)

Rate(H & K) = 60 A/5 hr or 12 A/hr
Rate (H) = 40 A/8 hr or 5 A/hr

Rate(K) = Rate(H & K) - Rate(H) = 12 - 5 = 7 A/hr

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by AleksandrM » Fri Jun 13, 2008 9:07 am
H is:

40 = 8r

r = 5 acres per hour

H and K for remaining 60:

5(5 + k) = 60

25 + 5k = 60

k = 7

A.
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