It is currently 17 Oct 2017, 03:02

### GMAT Club Daily Prep

#### 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

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

# Events & Promotions

###### Events & Promotions in June
Open Detailed Calendar

# The rear wheels of a car crossed a certain line 0.5 second

Author Message
TAGS:

### Hide Tags

Manager
Joined: 16 Feb 2012
Posts: 220

Kudos [?]: 408 [4], given: 121

Concentration: Finance, Economics
The rear wheels of a car crossed a certain line 0.5 second [#permalink]

### Show Tags

14 Jul 2012, 01:53
4
KUDOS
14
This post was
BOOKMARKED
00:00

Difficulty:

(N/A)

Question Stats:

71% (01:35) correct 29% (01:34) wrong based on 789 sessions

### HideShow timer Statistics

The rear wheels of a car crossed a certain line 0.5 second after the front wheels crossed the same line. If the centers of the front and rear wheels are 20 feet apart and the car traveled in a straight line at a constant speed, which of the following gives the speed of the car in miles per hour? (5280 feet = 1 mile)

A. $$(\frac{20}{5280})(\frac{60^2}{0.5})$$

B. $$(\frac{20}{5280})(\frac{60}{0.5})$$

C. $$(\frac{20}{5280})(\frac{0.5}{60^2})$$

D. $$\frac{(20)(5280)}{(60^2)(0.5)}$$

E. $$\frac{(20)(5280)}{(60)(0.5)}$$
[Reveal] Spoiler: OA

_________________

Kudos if you like the post!

Failing to plan is planning to fail.

Kudos [?]: 408 [4], given: 121

Math Expert
Joined: 02 Sep 2009
Posts: 41871

Kudos [?]: 128511 [0], given: 12179

Re: The rear wheels of a car crossed a certain line 0.5 second [#permalink]

### Show Tags

14 Jul 2012, 02:57
Expert's post
4
This post was
BOOKMARKED
Stiv wrote:
The rear wheels of a car crossed a certain line 0.5 second after the front wheels crossed the same line. If the centers of the front and rear wheels are 20 feet apart and the car traveled in a straight line at a constant speed, which of the following gives the speed of the car in miles per hour? (5280 feet = 1 mile)

A. $$(\frac{20}{5280})(\frac{60^2}{0.5})$$
B. $$(\frac{20}{5280})(\frac{60}{0.5})$$
C. $$(\frac{20}{5280})(\frac{0.5}{60^2})$$
D. $$\frac{(20)(5280)}{(60^2)(0.5)}$$
E. $$\frac{(20)(5280)}{(60)(0.5)}$$

We need to find the speed of the car in miles per hour. So, we should convert feet in miles and seconds in hours.

20 feet is $$\frac{20}{5280}$$ miles;
0.5 second is $$\frac{0.5}{3600}=\frac{0.5}{60^2}$$ hours;

The speed of the car therefore is $$\frac{distance}{time}=\frac{(\frac{20}{5280})}{(\frac{0.5}{60^2})}=(\frac{20}{5280})*(\frac{60^2}{0.5})$$.

Similar question to practice: a-train-traveling-at-a-constant-speed-down-a-straight-track-87124.html

Hope it helps.
_________________

Kudos [?]: 128511 [0], given: 12179

Math Expert
Joined: 02 Sep 2009
Posts: 41871

Kudos [?]: 128511 [0], given: 12179

Re: The rear wheels of a car crossed a certain line 0.5 second [#permalink]

### Show Tags

02 Jul 2013, 01:18
Bumping for review and further discussion*. Get a kudos point for an alternative solution!

*New project from GMAT Club!!! Check HERE

DS questions on Arithmetic: search.php?search_id=tag&tag_id=30
PS questions on Arithmetic: search.php?search_id=tag&tag_id=51

_________________

Kudos [?]: 128511 [0], given: 12179

Math Expert
Joined: 02 Sep 2009
Posts: 41871

Kudos [?]: 128511 [1], given: 12179

Re: The rear wheels of a car crossed a certain line 0.5 second [#permalink]

### Show Tags

02 Jul 2013, 01:18
1
KUDOS
Expert's post
2
This post was
BOOKMARKED

Kudos [?]: 128511 [1], given: 12179

Senior Manager
Joined: 13 May 2013
Posts: 463

Kudos [?]: 197 [0], given: 134

Re: The rear wheels of a car crossed a certain line 0.5 second [#permalink]

### Show Tags

05 Aug 2013, 13:31
The rear wheels of a car crossed a certain line 0.5 second after the front wheels crossed the same line. If the centers of the front and rear wheels are 20 feet apart and the car traveled in a straight line at a constant speed, which of the following gives the speed of the car in miles per hour? (5280 feet = 1 mile)

The car traveled 20 feet in 1/2 second. This means it traveled 40 feet a second or 2400 feet/minute. This equates to .45 miles a minute or roughly 27 miles/hour.

20/5280 * (60^2) / .5
20/5280 * 3600/.5
20/5280 * 7200
300/11 = roughly 27

Kudos [?]: 197 [0], given: 134

GMAT Club Legend
Joined: 09 Sep 2013
Posts: 16764

Kudos [?]: 273 [0], given: 0

Re: The rear wheels of a car crossed a certain line 0.5 second [#permalink]

### Show Tags

25 Feb 2015, 13:41
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.
_________________

Kudos [?]: 273 [0], given: 0

EMPOWERgmat Instructor
Status: GMAT Assassin/Co-Founder
Affiliations: EMPOWERgmat
Joined: 19 Dec 2014
Posts: 9962

Kudos [?]: 3397 [1], given: 172

Location: United States (CA)
GMAT 1: 800 Q51 V49
GRE 1: 340 Q170 V170
Re: The rear wheels of a car crossed a certain line 0.5 second [#permalink]

### Show Tags

25 Feb 2015, 23:29
1
KUDOS
Expert's post
Hi All,

Since this question is wordy and the answers are somewhat "crazy"-looking, it's possible that you might feel overwhelmed by this prompt. If you stay calm though and do the unit conversions properly, then you can use the answer choices to your advantage (and eliminate most of them for being too big or too small). Here's how:

The first step is to figure out approximately how fast the car was going. This will take a little bit of work, but the individual steps are not too hard.

The information in the first part of the question tells us that it basically takes .5 seconds to travel 20 feet. Since the question asks for a speed in MILES per HOUR, we have to convert these numbers....

.5 seconds = 20 feet
1 second = 40 feet
60 seconds = 2400 feet
1 hour = (2400)(60) = 144,000 feet

144,000 feet = about 28 miles

So the car was traveling about 28 miles per hour.

Now, by paying attention to how the answer choices are "structured", we can eliminate the wrong answers without having to calculate much...Remember that we're looking for an answer that is about 28.....

Let's start with Answers B and C, since they're the easiest to eliminate. Look at the NUMERATORS (relative to the DENOMINATORS)....

Answer B: 1200/2640. This is a FRACTION less than 1. Eliminate B.

Answer C: 10/(GIGANTIC PRODUCT). This is a REALLY small fraction. Eliminate C.

Of the remaining 3 answers, Answer E is reasonably easy to eliminate....

Answer E: (20)(5280)/30 This will be in the THOUSANDS. It's much too BIG. Eliminate E.

Between Answers A and D, notice how the "20" and the "0.5" are in the same relative positions.....

20/.05 = 40

So we're multiplying some fraction by 40. To get an answer that is equal to about 28, we need that fraction to be LESS than 1...

Answer A: 60^2/5280 is LESS than 1

Answer D: 5280/60^2 is GREATER than 1. Eliminate D.

[Reveal] Spoiler:
A

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

760+: Learn What GMAT Assassins Do to Score at the Highest Levels
Contact Rich at: Rich.C@empowergmat.com

# Rich Cohen

Co-Founder & GMAT Assassin

Special Offer: Save \$75 + GMAT Club Tests Free
Official GMAT Exam Packs + 70 Pt. Improvement Guarantee
www.empowergmat.com/

***********************Select EMPOWERgmat Courses now include ALL 6 Official GMAC CATs!***********************

Kudos [?]: 3397 [1], given: 172

GMAT Club Legend
Joined: 09 Sep 2013
Posts: 16764

Kudos [?]: 273 [0], given: 0

Re: The rear wheels of a car crossed a certain line 0.5 second [#permalink]

### Show Tags

29 Jul 2016, 03:17
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.
_________________

Kudos [?]: 273 [0], given: 0

GMAT Club Legend
Joined: 09 Sep 2013
Posts: 16764

Kudos [?]: 273 [0], given: 0

Re: The rear wheels of a car crossed a certain line 0.5 second [#permalink]

### Show Tags

29 Aug 2017, 06:14
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.
_________________

Kudos [?]: 273 [0], given: 0

Target Test Prep Representative
Affiliations: Target Test Prep
Joined: 04 Mar 2011
Posts: 1545

Kudos [?]: 826 [0], given: 5

Re: The rear wheels of a car crossed a certain line 0.5 second [#permalink]

### Show Tags

01 Sep 2017, 12:05
Stiv wrote:
The rear wheels of a car crossed a certain line 0.5 second after the front wheels crossed the same line. If the centers of the front and rear wheels are 20 feet apart and the car traveled in a straight line at a constant speed, which of the following gives the speed of the car in miles per hour? (5280 feet = 1 mile)

A. $$(\frac{20}{5280})(\frac{60^2}{0.5})$$

B. $$(\frac{20}{5280})(\frac{60}{0.5})$$

C. $$(\frac{20}{5280})(\frac{0.5}{60^2})$$

D. $$\frac{(20)(5280)}{(60^2)(0.5)}$$

E. $$\frac{(20)(5280)}{(60)(0.5)}$$

We see that the car drives 20 ft in 0.5 seconds. Since the car drives at a constant speed, its rate o is 20 ft/0.5 seconds.

Let’s convert 20 ft/0.5 sec into mph:

20 ft/0.5 sec x 1 mi/5280 ft x 3600 sec/1 hr

In the above expression, we see the units “seconds” and “feet” will cancel and we are left with:

(20 x 1 x 3600)/(0.5 x 5280 x 1) mi/hr

(20 x 3600)/(0.5 x 5280) mi/hr

_________________

Jeffery Miller

GMAT Quant Self-Study Course
500+ lessons 3000+ practice problems 800+ HD solutions

Kudos [?]: 826 [0], given: 5

Re: The rear wheels of a car crossed a certain line 0.5 second   [#permalink] 01 Sep 2017, 12:05
Display posts from previous: Sort by

# The rear wheels of a car crossed a certain line 0.5 second

 Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne Kindly note that the GMAT® test is a registered trademark of the Graduate Management Admission Council®, and this site has neither been reviewed nor endorsed by GMAC®.