Jim can assemble b crates in an hour and Robert

Expert replies

M7MBA: Moderator; Posts: 2058; Joined: Sun Oct 29, 2017 4:24 amFollowed by: 5 members; Thanked: 1 times

by M7MBA » Sun Dec 17, 2017 8:34 am

Jim can assemble b crates in an hour and Robert can assemble 2b crates in an hour. Working together at this rate, how many crates can they assemble in four hours?

A) 3b

B) 6b

C) 8b

D) 12b

E) 18b

The OA is D.

Which is the equation I should set to solve this PS question? Experts, may you give me some help, please?

Like this post

Source: Beat The GMAT — Problem Solving | Sun Dec 17, 2017 8:34 am

EconomistGMATTutor: GMAT Instructor; Posts: 555; Joined: Wed Oct 04, 2017 4:18 pmFollowed by: 12 members; Thanked: 180 times

Jim can assemble b crates in an hour and Robert

by EconomistGMATTutor » Sun Dec 17, 2017 10:57 am

Jim can assemble b crates in an hour and Robert can assemble 2b crates in an hour. Working together at this rate, how many crates can they assemble in four hours?

A) 3b

B) 6b

C) 8b

D) 12b

E) 18b

The OA is D.

Which is the equation I should set to solve this PS question? Experts, may you give me some help, please?

Hi M7MBA,
Let's take a look at your question.

$$\text{Jim's rate }\ =\ \frac{b}{1}=b$$
$$\text{Robert's rate}\ =\ \frac{2b}{1}=2b$$
$$\text{Jim and Robert's combined rate}\ = b+2b=3b$$

Working together number of crates they assemble in 1 hour = 3b
Working together number of crates they assemble in 4 hour = 3b * 4 = 12b

Therefore, Option D is correct.

Hope it helps.
I am available if you'd like any follow up.

GMAT Prep From The Economist
We offer 70+ point score improvement money back guarantee.
Our average student improves 98 points.

Like this post

GMAT/MBA Expert

[email protected]: Elite Legendary Member; Posts: 10392; Joined: Sun Jun 23, 2013 6:38 pmFollowed by: 511 members; Location: Palo Alto, CA; Thanked: 2867 times; GMAT Score:800

by [email protected] » Sun Dec 17, 2017 1:49 pm

Hi M7MBA,

We're told that Jim can assemble B crates in an hour and Robert can assemble 2B crates in an hour. We're asked for the total number of crates that the two of them can assemble in four hours. This question can be solved Algebraically or by TESTing VALUES.

Using Algebra, you know the number of crates assembled by the two people in 1 hour (B+2B = 3B per hour). Thus, over 4 hours, you have (4)(3B) = 12B crates

TESTing VALUES, if... B = 2
Jim assembles 2 crates/hour
Robert assembles 4 crates/hour
Total = 6 crates an hour
In 4 hours.... (4)(6) = 24 crates are assembled.

Thus, we're looking for an answer that equals 24 when B=2. There's only one answer that matches.

Final Answer: D

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

Contact Rich at [email protected]

Like this post

GMAT/MBA Expert

Brent@GMATPrepNow: GMAT Instructor; Posts: 16207; Joined: Mon Dec 08, 2008 6:26 pmFollowed by: 1268 members; Location: Vancouver, BC; Thanked: 5254 times; GMAT Score:770

by Brent@GMATPrepNow » Sun Dec 17, 2017 1:55 pm

M7MBA wrote:Jim can assemble b crates in an hour and Robert can assemble 2b crates in an hour. Working together at this rate, how many crates can they assemble in four hours?

A) 3b

B) 6b

C) 8b

D) 12b

E) 18b

We can also apply some logic to solve this question

Given: Jim can assemble b crates in 1 hour
So: Jim can assemble 2b crates in 2 hours [if we double the work time, we double the output]
So: Jim can assemble 4b crates in 4 hours [if we double the work time (again), we double the output]

Given: Robert can assemble 2b crates in 1 hour
So: Robert can assemble 4b crates in 2 hours [if we double the work time, we double the output]
So: Robert can assemble 8b crates in 4 hours [if we double the work time (again), we double the output]

So, when we COMBINE their efforts, we add their 4-hour OUTPUTS
That is, TOTAL output = color=red]4b[/color] + color=red]8b[/color] = 12b

Answer: D

Cheers,
Brent

Brent Hanneson - Creator of GMATPrepNow.com

Like this post

GMAT/MBA Expert

Scott@TargetTestPrep: GMAT Instructor; Posts: 8177; Joined: Sat Apr 25, 2015 10:56 amFollowed by: 29 members; Location: Los Angeles, CA; Thanked: 43 times

by Scott@TargetTestPrep » Mon Sep 16, 2019 10:20 am

M7MBA wrote:Jim can assemble b crates in an hour and Robert can assemble 2b crates in an hour. Working together at this rate, how many crates can they assemble in four hours?

A) 3b

B) 6b

C) 8b

D) 12b

E) 18b

The OA is D.

Which is the equation I should set to solve this PS question? Experts, may you give me some help, please?

In 4 hours Jim and Robert can assemble b x 4 + 2b x 4 = 12b crates.

Answer: D

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

Like this post

Post new topic Post Reply

• Page 1 of 1

GMAT Course Reviews

560 reviews

1168 reviews

431 reviews

359 reviews

147 reviews

5/5

5 Star (560 Reviews)

"Target Test Prep is the closest to the official version of the GMAT exam, about 99% accuracy in terms of the quality and quantity of information. The course has excellently created singular sets of focused lessons and tests for every possible topic that one could come across in the official GMAT exam."

"The TTP course maximizes the efficiency of the time you spend studying. It will take time and effort but I could almost guarantee that if you complete the course exactly as it is laid out you will get an amazing score. They also have a very responsive team willing to help with any questions you might have."

"TTP has two things that I think no other test prep company offers: A teaching approach that reinforces understanding and an attitude that will give you the mental preparedness needed to succeed on the test. TTP gives you a deep understanding of the concept you need to know while teaching you how to think."

Write a Review