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?
At this rate, how many bolts could 4 such machines produce..
This topic has expert replies
GMAT/MBA Expert
- Brent@GMATPrepNow
- GMAT Instructor
- Posts: 16207
- Joined: Mon Dec 08, 2008 6:26 pm
- Location: Vancouver, BC
- Thanked: 5254 times
- Followed by:1268 members
- GMAT Score:770
The "a" represents a variable.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
The OA is E.
The question would be clearer if it read as follows:
Cheers,Running at the same constant rate, k 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) k/6
(B) k/600
(C) 150/k
(D) 480/k
(E) 2,400/k
Brent
GMAT/MBA Expert
- Brent@GMATPrepNow
- GMAT Instructor
- Posts: 16207
- Joined: Mon Dec 08, 2008 6:26 pm
- Location: Vancouver, BC
- Thanked: 5254 times
- Followed by:1268 members
- GMAT Score:770
We can solve this question using equivalent ratios.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
The OA is E.
Given: a identical machines produce a total of 120 bolts per ONE minute
So, a identical machines produce a total of 600 bolts per FIVE minutes
How many bolts could 4 such machines produce in 5 minutes?
Let x = the number of bolts 4 machines can produce in 5 minutes
We get: a/600 = 4/x
Cross multiply to get: ax = (600)(4)
Simplify to get: ax = 2400
Divide both sides by a to get: x = 2400/a
Answer: E
Cheers,
Brent
- GMATGuruNY
- GMAT Instructor
- Posts: 15539
- Joined: Tue May 25, 2010 12:04 pm
- Location: New York, NY
- Thanked: 13060 times
- Followed by:1906 members
- GMAT Score:790
Let a=1, implying that 1 machine produces 120 bolts per minute.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
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.
The correct answer is E.
Private tutor exclusively for the GMAT and GRE, with over 20 years of experience.
Followed here and elsewhere by over 1900 test-takers.
I have worked with students based in the US, Australia, Taiwan, China, Tajikistan, Kuwait, Saudi Arabia -- a long list of countries.
My students have been admitted to HBS, CBS, Tuck, Yale, Stern, Fuqua -- a long list of top programs.
As a tutor, I don't simply teach you how I would approach problems.
I unlock the best way for YOU to solve problems.
For more information, please email me (Mitch Hunt) at [email protected].
Student Review #1
Student Review #2
Student Review #3
Followed here and elsewhere by over 1900 test-takers.
I have worked with students based in the US, Australia, Taiwan, China, Tajikistan, Kuwait, Saudi Arabia -- a long list of countries.
My students have been admitted to HBS, CBS, Tuck, Yale, Stern, Fuqua -- a long list of top programs.
As a tutor, I don't simply teach you how I would approach problems.
I unlock the best way for YOU to solve problems.
For more information, please email me (Mitch Hunt) at [email protected].
Student Review #1
Student Review #2
Student Review #3
GMAT/MBA Expert
- Scott@TargetTestPrep
- GMAT Instructor
- Posts: 7223
- Joined: Sat Apr 25, 2015 10:56 am
- Location: Los Angeles, CA
- Thanked: 43 times
- Followed by:29 members
We are given that the rate of a machines is 120. Thus, the rate of 4 machines is: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
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.
Answer: E
Scott Woodbury-Stewart
Founder and CEO
[email protected]
See why Target Test Prep is rated 5 out of 5 stars on BEAT the GMAT. Read our reviews