Welcome! Check out our free B-School Guides to learn how you compare with other applicants.

## OG 129 - rounding problem

This topic has 1 expert reply and 3 member replies
Fractal Really wants to Beat The GMAT!
Joined
22 Aug 2010
Posted:
183 messages
Followed by:
1 members
Thanked:
5 times
Test Date:
24.09.2011
Target GMAT Score:
700
OG 129 - rounding problem Sun Jul 10, 2011 6:06 am
Elapsed Time: 00:00
• Lap #[LAPCOUNT] ([LAPTIME])
... Cindy drove her car 290 miles, rounded to the nearest 10 miles, and...

--> so I thought that it could actually be 285 up to 294 miles

BUT: according to OG, it could be 285 up to 295

I don't understand, since 295 should be rounded up to 300?!

thx

Need free GMAT or MBA advice from an expert? Register for Beat The GMAT now and post your question in these forums!
vineeshp GMAT Destroyer!
Joined
28 Jan 2010
Posted:
965 messages
Followed by:
35 members
Thanked:
154 times
Test Date:
9th Feb 2010
GMAT Score:
720
Sun Jul 10, 2011 7:25 am
Please make sure you post the full question always. You cannot expect the reader to go back to the OG and get the question.

Ok I just read the question.

You have to work with what is given.
Tha answer would be between the values given in D. So D is the correct answer. If you see clearly, no other answer can get you to the right answer.

_________________
Vineesh,
Just telling you what I know and think. I am not the expert.

rdelaure Just gettin' started!
Joined
04 Mar 2012
Posted:
1 messages
Mon Mar 12, 2012 11:01 am
I completely agree I am confused by the reasoning provided in the OG.
The question states, on a recent trip , cindy drove her car 290 miles, rounded to the nearest 10 miles, and used 12 gallons of gasoline, rounded to the nearest gallon. The actual number of miles cindy car got on this trip must have been between>
None of which fit to my understanding of rounding..
The OG states the answer is found from making a range for miles and for gallons, then putting the lowest number of miles per gallon:
284/12.5
and the Highest number of miles per gallon:
295/11.4

I would think with rounding to the nearest 10 miles the range is from 285 to 294, otherwise if it is 295, then in the problem it should be rounded to 300, not down to 290 as it was in the problem.
Same problem with the min and max rounding they provided for gallons. I would have put the range at: 11.5 to 12.4

Writing in 2 days so really appreciate an experts view on this one !!

thank you

Snowbirds Just gettin' started!
Joined
11 Mar 2012
Posted:
5 messages
Tue Mar 13, 2012 2:28 am
The point is that the OG is helping you learn to estimate. Your range of 285 to 294 is actually LESS accurate than the OG? Why? What is the answer if you were to round 294.99999999? That's NEARLY 295, so why not simplify and estimate with 295? Your answer of 294 is 1 full mile away from the max.

Obviously both numbers are estimates, but the OGs is in fact the closest estimate available.

Hope that helps...

### GMAT/MBA Expert

GMATGuruNY GMAT Instructor
Joined
25 May 2010
Posted:
6216 messages
Followed by:
1064 members
Thanked:
5430 times
GMAT Score:
790
Tue Mar 13, 2012 7:10 am
Quote:
On a recent trip, Cindy drove her car 290 miles, rounded to the nearest 10 miles, and used 12 gallons of gasoline, rounded to the nearest gallon. The actual number of miles per gallon that Cindy's car got on this trip must have been between

A) 290/12.5 to 290/11.5

B) 295/12 to 285/11.5

C) 285/12 to 295/12

D) 285/12.5 to 295/11.5

E) 205/12.5 to 285/11.5
We round UP when we reach the HALFWAY point between two values.
Any value BELOW the halfway point is rounded DOWN.

290 miles, rounded to the nearest 10 miles:
285 ≤ m < 295.
Please note that 295 is the UPPER LIMIT.
Any value below 295 -- even 294.999 -- is rounded DOWN to 290.

12 gallons of gasoline, rounded to the nearest gallon:
11.5 ≤ g < 12.5.
Please note that 12.5 is the UPPER LIMIT.
Any value below 12.5 -- even 12.499 -- is rounded DOWN to 12.

Worst miles per gallon = (lower limit for miles)/(upper limit for gas) = 285/12.5.
Best miles per gallon = (upper limit for miles)/(lower limit for gas) = 295/11.5.
Thus, miles per gallon is between 285/12.5 and 295/11.5.

_________________
Mitch Hunt
GMAT Private Tutor and Instructor
GMATGuruNY@gmail.com
If you find one of my posts helpful, please take a moment to click on the "Thank" icon.
Contact me about long distance tutoring!

Thanked by: rdelaure
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.

### Best Conversation Starters

1 vipulgoyal 30 topics
2 hemant_rajput 21 topics
3 guerrero 18 topics
4 abhirup1711 17 topics
5 sana.noor 16 topics
See More Top Beat The GMAT Members...

### Most Active Experts

1 Brent@GMATPrepNow

GMAT Prep Now Teacher

209 posts
2 GMATGuruNY

The Princeton Review Teacher

134 posts
3 Jim@StratusPrep

Stratus Prep

60 posts