GMAT Prep - Q37

Question

Final question. Thanks!!! DOH, I'm an idiot. I misread one part of the question. Ugh. Sorry.

aim-wsc · Answer

I dont know if you still looking for answer//// :roll: Here it goes. H= (40/8 ) = 5 acres per hour H+K= (60/5) =12 K=12-5=7. Whats the original answer btw?

aficionado · Answer

has to be 7 (A).

Cybermusings · Answer

I think your answer is fine. It is 7 H - 8 hours - 40 acres ; 5 acres in 1 hour H + K - 5 hours - 60 acres ; 12 acres in 1 hour Thus K alone = 12 - 5 = 7 acres in 1 hour

BTGmoderatorRO · Answer

The farm used two harvesting machines H and K
H alone harvested 40 acres of wheat in 8 hours
H and K harvested 60 acres of wheat in 5 hours

To get the harvested acres of machine K per hour,
---since H alone harvested 40 acres of wheat in 8 hours, we divide the acres and hours by 8 in order to get the harvest per hour.

(40 acres/8) of wheat in 8 hours/ 8
H = 5 acres of wheat in one hour

--- Also to get H and K harvest per hour, we can say that,
60 acres of wheat in 5 hours. we also divide the acres and hours by 5 hours in order to get the harvest per hour,
(40 acres/8) of wheat in 5 hours/ 5
H and K = 12 acres of wheat in 1 hour

finally to get the harvest of machine K per hour, we can see that both H and K harvested 12 acres per hour and H harvested 5 acres per hour. So, the harvest of K per hour = 12 - 5 = 7 acres per hour

EconomistGMATTutor · Answer

maxim730 wrote:Final question. Thanks!!!

DOH, I'm an idiot. I misread one part of the question. Ugh. Sorry.

Hi Maxim730,

Let's take a look at your question.

The question states that harvesting machine H, working alone harvest 40 acres of wheat in 8 hours.

We can calculate the rate of harvesting machine H per hour as:
40/8 = 5 acres/hour

Harvesting Machine H harvests at a rate of 5 acres/hr.
H = 5acres/hr --- (i)

Next fact the question states is that harvesting machines H and K, working together harvested the remaining acres of wheat in 5 hours.

Rest of acres of wheat = 100 - 40 = 60
Now, we will calculate the rate of harvesting per hour for both the machines working together as:
60/5 = 12 acres/hour

H + K = 12 acres/hr ... (ii)

From Eq(i) and (ii), we can now find the harvesting rate for Machine K by plugging in the value of H in eq(ii),

H + 5 = 12
H = 12 - 5
H = 7 acres/ hr

Therefore, 7 is the correct answer.

I am available if you'd like any followup.

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Scott@TargetTestPrep · Answer

maxim730 wrote: ↑Wed Mar 14, 2007 6:26 pm Final question. Thanks!!! DOH, I'm an idiot. I misread one part of the question. Ugh. Sorry. Solution: The rate of harvesting machine H is 40/8 = 5 acres per hour. We can let the rate of harvesting machine K = k acres per hour. Thus, the combined rate of machines K and H is 5 + k, and we are given that they harvest 60 acres in 5 hours; thus: (5 + k) x 5 = 60 5 + k = 12 k = 7 Alternate Solution: Machine H harvests 40 acres in 8 hours; thus, it harvests 40/8 = 5 acres per hour. It would take the same machine 60/5 = 12 hours to harvest the remaining 100 - 40 = 60 acres. We are given that machines H and K working together can harvest 60 acres in 5 hour; therefore, in one hour, they complete 1/5 of the 60 acres. Since machine H does the same job alone in 12 hours, it completes 1/12 of the 60 acres in one hour. Thus, machine K alone can complete 1/5 - 1/12 = 12/60 - 5/60 = 7/60 of the 60 acres. Then, it takes machine K 60/7 hours to harvest 60 acres, and in one hour, machine K can harvest 60/(60/7) = 7 acres. Answer: A

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