A farm used two harvesting machines, H and K, to harvest 100 acres of

Question

A farm used two harvesting machines, H and K, to harvest 100 acres of wheat. Harvesting machine H, working alone at its constant rate, harvested 40 acres of wheat in 8 hours. Then harvesting machine K was brought in, and harvesting machines H and K, working together at their respective constant rates, harvested the remaining acres of wheat in 5 hours. Harvesting machine K harvested how many acres of wheat per hour?

(A) 7
(B) 8
(C) 12
(D) 13
(E) 15

(A) 7
(B) 8
(C) 12
(D) 13
(E) 15

Kurtosis · Accepted Answer

Rate of H = 5 acres/hr

Remaining land to be harvested = 100 - 40 = 60

Rate of H and K = 60/5 = 12 acres/hr

Rate of K = 12 - 5 = 7

Answer: A

tapabrata · Answer

H harvests 40 acres in 8 hours.
Therefore in 1 hour, H harvests 40/8 = 5 acres

Remaining 60 acres was harvested by H and K together in 5 hours.
Therefore in 1 hour, H and K harvested 60/5 = 12 acres

In the 1 hour that H and K worked together, H alone harvested 5 acres.
So the remaining acres (12-5)=7 acres was harvested by K.

So K harvested 7 acres/hour.

Answer A

KrishnakumarKA1 · Answer

rate of H = 40/8 = 5 acre/hr
H also worked for 5 hours
There in 5 hours H harvested 5*5 = 25acre
left is 60-25 = 35 acres which is harvested by K
therefore rate of K = 35/5 = 7 acre/hr

Option A

ScottTargetTestPrep · Answer

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

Answer: A

EMPOWERgmatRichC · Answer

Hi All,

We're told that a farm used two harvesting Machines, H and K, to harvest 100 acres of wheat. Harvesting Machine H, working alone at its constant rate, harvested 40 acres of wheat in 8 hours. Then harvesting Machine K was brought in, and harvesting Machines H and K, working together at their respective constant rates, harvested the remaining acres of wheat in 5 hours. We're asked for Machine K's harvesting rate in acres of wheat per hour. While this question is wordy, it just comes down to some basic note-taking and Arithmetic.

Since Machine H harvested 40 acres in 8 hours, we know that H's harvesting rate is 40/8 = 5 acres/hour

Machine H and Machine K then harvested together for 5 hours: 
Machine H harvested (5)(5 acres/hour) = 25 acres 
In total, Machine H harvested 40+25 = 65 of the 100 total acres, which leaves 35 acres for Machine K to harvest over those 5 hours. 
Machine K = 35 acres/5 hours = 7 acres/hour

Final Answer:  A

GMAT assassins aren't born, they're made, 
Rich

CrackverbalGMAT · Answer

Let us try to analyze the rate of working alone by H and K and that of working together.

Working together, they harvested 60 acres in 12 hours

Rate(H & K) that is the rate of working together = 60 Acres in 5 hours

or 12 Acres/hour

Rate of working of H = 40 Acres in 8 hours or 5 Acres/hour

Rate of working of K that is harvesting done by K every hour = Rate(H & K) - Rate(H)

= 12 - 5
 
= 7 Acres/hr.

(option a)

Devmitra Sen
GMAT SME

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