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## At this rate, how many bolts could 4 such machines produce..

tagged by: Brent@GMATPrepNow

This topic has 4 expert replies and 0 member replies

### Top Member

Vincen Master | Next Rank: 500 Posts
Joined
07 Sep 2017
Posted:
458 messages
6

#### At this rate, how many bolts could 4 such machines produce..

Tue Sep 12, 2017 11:00 am
Running at the same constant rate, "a" identical machines can produce a total of 120 bolts per minute. At this rate, how many bolts could 4 such machines produce in 5 minutes?

(A) a/6
(B) a/600
(C) 150/a
(D) 480/a
(E) 2,400/a

The OA is E.

I am very confuse here. Who is "a"? and why is E?

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### GMAT/MBA Expert

Scott@TargetTestPrep GMAT Instructor
Joined
25 Apr 2015
Posted:
548 messages
Followed by:
3 members
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Wed Sep 20, 2017 2:43 pm
Vincen wrote:
Running at the same constant rate, "a" identical machines can produce a total of 120 bolts per minute. At this rate, how many bolts could 4 such machines produce in 5 minutes?

(A) a/6
(B) a/600
(C) 150/a
(D) 480/a
(E) 2,400/a
We are given that the rate of a machines is 120. Thus, the rate of 4 machines is:

a/120 = 4/x

ax = 480

x = 480/a

Since the rate of 4 machines is 480/a bolts per minute, 4 machines can produce 480/a * 5 = 2400/a bolts in 5 minutes.

_________________

Scott Woodbury Stewart Founder & CEO
GMAT Quant Self-Study Course - 500+ lessons 3000+ practice problems 800+ HD solutions
5-Day Free Trial 5-DAY FREE, FULL-ACCESS TRIAL TTP QUANT

Thanked by: Vincen

### GMAT/MBA Expert

GMATGuruNY GMAT Instructor
Joined
25 May 2010
Posted:
13608 messages
Followed by:
1796 members
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GMAT Score:
790
Tue Sep 12, 2017 2:36 pm
Vincen wrote:
Running at the same constant rate, "a" identical machines can produce a total of 120 bolts per minute. At this rate, how many bolts could 4 such machines produce in 5 minutes?

(A) a/6
(B) a/600
(C) 150/a
(D) 480/a
(E) 2,400/a
Let a=1, implying that 1 machine produces 120 bolts per minute.
Since 1 machine produces 120 bolts per minute, the rate for 4 machines = 4*120 = 480 bolts per minute.
At a rate of 480 bolts per minute, the number of bolts produced by the 4 machines in 5 minutes = rt = 480*5 = 2400 bolts. This is our target.

Now plug a=1 into the answer choices to see which yield the target value of 2400.
Only E works:
2400/a = 2400/1 = 2400.

_________________
Mitch Hunt
GMAT Private Tutor
GMATGuruNY@gmail.com
If you find one of my posts helpful, please take a moment to click on the "Thank" icon.
Available for tutoring in NYC and long-distance.

Thanked by: Vincen
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### GMAT/MBA Expert

Scott@TargetTestPrep GMAT Instructor
Joined
25 Apr 2015
Posted:
548 messages
Followed by:
3 members
43
Wed Sep 20, 2017 2:43 pm
Vincen wrote:
Running at the same constant rate, "a" identical machines can produce a total of 120 bolts per minute. At this rate, how many bolts could 4 such machines produce in 5 minutes?

(A) a/6
(B) a/600
(C) 150/a
(D) 480/a
(E) 2,400/a
We are given that the rate of a machines is 120. Thus, the rate of 4 machines is:

a/120 = 4/x

ax = 480

x = 480/a

Since the rate of 4 machines is 480/a bolts per minute, 4 machines can produce 480/a * 5 = 2400/a bolts in 5 minutes.

_________________

Scott Woodbury Stewart Founder & CEO
GMAT Quant Self-Study Course - 500+ lessons 3000+ practice problems 800+ HD solutions
5-Day Free Trial 5-DAY FREE, FULL-ACCESS TRIAL TTP QUANT

Thanked by: Vincen

### GMAT/MBA Expert

GMATGuruNY GMAT Instructor
Joined
25 May 2010
Posted:
13608 messages
Followed by:
1796 members
13060
GMAT Score:
790
Tue Sep 12, 2017 2:36 pm
Vincen wrote:
Running at the same constant rate, "a" identical machines can produce a total of 120 bolts per minute. At this rate, how many bolts could 4 such machines produce in 5 minutes?

(A) a/6
(B) a/600
(C) 150/a
(D) 480/a
(E) 2,400/a
Let a=1, implying that 1 machine produces 120 bolts per minute.
Since 1 machine produces 120 bolts per minute, the rate for 4 machines = 4*120 = 480 bolts per minute.
At a rate of 480 bolts per minute, the number of bolts produced by the 4 machines in 5 minutes = rt = 480*5 = 2400 bolts. This is our target.

Now plug a=1 into the answer choices to see which yield the target value of 2400.
Only E works:
2400/a = 2400/1 = 2400.

_________________
Mitch Hunt
GMAT Private Tutor
GMATGuruNY@gmail.com
If you find one of my posts helpful, please take a moment to click on the "Thank" icon.
Available for tutoring in NYC and long-distance.

Thanked by: Vincen
Free GMAT Practice Test How can you improve your test score if you don't know your baseline score? Take a free online practice exam. Get started on achieving your dream score today! Sign up now.

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