Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized for You

we will pick new questions that match your level based on your Timer History

Track Your Progress

every week, we’ll send you an estimated GMAT score based on your performance

Practice Pays

we will pick new questions that match your level based on your Timer History

Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.

It appears that you are browsing the GMAT Club forum unregistered!

Signing up is free, quick, and confidential.
Join other 500,000 members and get the full benefits of GMAT Club

Registration gives you:

Tests

Take 11 tests and quizzes from GMAT Club and leading GMAT prep companies such as Manhattan GMAT,
Knewton, and others. All are free for GMAT Club members.

Applicant Stats

View detailed applicant stats such as GPA, GMAT score, work experience, location, application
status, and more

Books/Downloads

Download thousands of study notes,
question collections, GMAT Club’s
Grammar and Math books.
All are free!

Thank you for using the timer!
We noticed you are actually not timing your practice. Click the START button first next time you use the timer.
There are many benefits to timing your practice, including:

WE 1: 7 Yrs in Automobile (Commercial Vehicle industry)

During the last four years, a large truck company purchased [#permalink]

Show Tags

07 Aug 2012, 13:40

1

This post was BOOKMARKED

00:00

A

B

C

D

E

Difficulty:

5% (low)

Question Stats:

93% (01:19) correct
7% (01:52) wrong based on 46 sessions

HideShow timer Statistics

During the last four years, a large truck company purchased diesel at rates of $1.2, $1.4, $1.8 and $2.1 per gallon. What was the mean cost of diesel over the four-year period if the company spends the same amount of dollars on diesel each year?

Official Answer and Stats are available only to registered users. Register/Login.

_________________

Regards SD ----------------------------- Press Kudos if you like my post. Debrief 610-540-580-710(Long Journey): http://gmatclub.com/forum/from-600-540-580-710-finally-achieved-in-4th-attempt-142456.html

During the last four years, a large truck company purchased diesel at rates of $1.2, $1.4, $1.8 and $2.1 per gallon. What was the mean cost of diesel over the four-year period if the company spends the same amount of dollars on diesel each year?

A) $2.5 B) $2.55 C) $1.55 D) $3.25 E) $3.0

Source: 4gmat

Think of the numbers as 12, 14, 18, 21 LCM = 12*7*3

Assume the company spent $12*21 each year on diesel. Amount of diesel bought in 1st year = 21 gallons, 2nd year = 18 gallons, 3rd year = 14 gallons, 4th year = 12 gallons

Avg cost of diesel = 12*21*4/(21 + 18 + 14 + 12) = 12*21*4/65 = 15.5 (painful calculation here! I don't expect this in GMAT)

Since we ignored the decimal, the actual mean cost is 1.55. Answer (C)

Actually, what what you are doing is finding the Harmonic mean here.

HM = 4/(1/12 + 1/14 + 1/18 + 1/21) = 15.5 The calculation is the same either way.
_________________

During the last four years, a large truck company purchased diesel at rates of $1.2, $1.4, $1.8 and $2.1 per gallon. What was the mean cost of diesel over the four-year period if the company spends the same amount of dollars on diesel each year?

A. $2.5 B. $2.55 C. $1.55 D. $3.25 E. $3.0

Source: 4gmat

5 second approach:

On the PS section one should always look at the answer choices before starts to solve a problem.

The average cost cannot possibly be more than $2.1 per gallon (the largest amount payed per gallon in four-year period). Hence only answer choice C can be the correct answer.

Re: During the last four years, a large truck company purchased [#permalink]

Show Tags

09 Aug 2012, 18:33

VeritasPrepKarishma wrote:

SOURH7WK wrote:

During the last four years, a large truck company purchased diesel at rates of $1.2, $1.4, $1.8 and $2.1 per gallon. What was the mean cost of diesel over the four-year period if the company spends the same amount of dollars on diesel each year?

A) $2.5 HM = 4/(1/12 + 1/14 + 1/18 + 1/21) = 15.5 The calculation is the same either way.

Karishma sorry for such a basic question, but how do you calculate the LCM between different numbers, im forgetting my basics here..
_________________

How to improve your RC score, pls Kudo if helpful! http://gmatclub.com/forum/how-to-improve-my-rc-accuracy-117195.html Work experience (as of June 2012) 2.5 yrs (Currently employed) - Mckinsey & Co. (US Healthcare Analyst) 2 yrs - Advertising industry (client servicing)

Karishma sorry for such a basic question, but how do you calculate the LCM between different numbers, im forgetting my basics here..

LCM is the lowest common multiple. To get the LCM of some numbers, you split the number into its prime factors.

\(12 = 2^2 * 3\) \(18 = 2*3^2\) \(24 = 2^3*3\)

Now LCM is the number that includes all the factors of each of these numbers.

\(LCM = 2^3 * 3^2 = 72\)

We take 2^3 because the highest power of 2 in any number is 2^3 so we need at least three 2s in the LCM. We take 3^2 because the highest power of 3 in any number is 3^2 so we need at least two 3s in the LCM.

Instead, if the numbers are:

\(12 = 2^2 * 3\) \(14 = 2*7\) \(LCM = 2^2*3*7\)

When looking for LCM of 12, 14, 18, 21, we know that the LCM must have each of these numbers as the factor. So I took 12 since the first number is 12. 14 has 2 which is already included in 12 and it has 7 which is not included in 12 so we need to take a 7 too. We get 12*7 18 has a 2 which is already included in 12 and it has two 3s but 12 has only one 3. So we need another 3. We get 12*7*3 21 has 3 and 7 and they both are already included.

Re: During the last four years, a large truck company purchased [#permalink]

Show Tags

04 Dec 2015, 11:28

Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
_________________

Version 8.1 of the WordPress for Android app is now available, with some great enhancements to publishing: background media uploading. Adding images to a post or page? Now...

Post today is short and sweet for my MBA batchmates! We survived Foundations term, and tomorrow's the start of our Term 1! I'm sharing my pre-MBA notes...

“Keep your head down, and work hard. Don’t attract any attention. You should be grateful to be here.” Why do we keep quiet? Being an immigrant is a constant...