Rounding Numbers Confusion..

This topic has expert replies
User avatar
Senior | Next Rank: 100 Posts
Posts: 35
Joined: Wed Jul 24, 2013 10:15 am
Thanked: 2 times

Rounding Numbers Confusion..

by ProGMAT » Fri Aug 16, 2013 12:47 am

Timer

00:00

Your Answer

A

B

C

D

E

Global Stats

If d = 2.0453 and d* is the decimal obtained by rounding d to the nearest hundredth, what is the value of d* - d ?
(A) -0.0053
(8) -0.0003
(C) 0.0007
(D) 0.0047
(E) 0.0153
Source: — Problem Solving |

User avatar
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

by GMATGuruNY » Fri Aug 16, 2013 3:00 am
ProGMAT wrote:If d = 2.0453 and d* is the decimal obtained by rounding d to the nearest hundredth, what is the value of d* - d ?
(A) -0.0053
(8) -0.0003
(C) 0.0007
(D) 0.0047
(E) 0.0153
d = 2.0453.
Since the digit to the right of the hundredth digit is 5 or greater, we round UP to the nearest hundredth:
2.0453 --> 2.05.

Thus:
*d - d = 2.0500 - 2.0453= 0.0047.

The correct answer is D.
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

User avatar
Senior | Next Rank: 100 Posts
Posts: 35
Joined: Wed Jul 24, 2013 10:15 am
Thanked: 2 times

by ProGMAT » Fri Aug 16, 2013 3:25 am
GMATGuruNY wrote:
ProGMAT wrote:If d = 2.0453 and d* is the decimal obtained by rounding d to the nearest hundredth, what is the value of d* - d ?
(A) -0.0053
(8) -0.0003
(C) 0.0007
(D) 0.0047
(E) 0.0153
d = 2.0453.
Since the digit to the right of the hundredth digit is 5 or greater, we round UP to the nearest hundredth:
2.0453 --> 2.05.

Thus:
*d - d = 2.0500 - 2.0453= 0.0047.

The correct answer is D.
Thanks for the solution GMATGuruNY.
But i am confused as in some solutions in OG, the round off rang of a number is till next 5 pointer. Example: range of 4 is from 3.5 to 4.5. Why is that so?

User avatar
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

by GMATGuruNY » Fri Aug 16, 2013 3:38 am
ProGMAT wrote: Example: range of 4 is from 3.5 to 4.5. Why is that so?
The given range is not quite correct.
If x is rounded to the nearest integer, the following range is rounded to 4:
3.5 ≤ x < 4.5.
Any value LESS than 4.5 is rounded DOWN to 4.
But once we reach HALFWAY between 4 and 5 -- once we reach 4.5 -- we round UP to 5.
Thus:
Any value of x such that 4.5≤x<5 is rounded UP to 5.

For more on rounding, check my posts here:
https://www.beatthegmat.com/decimals-t267013.html
https://www.beatthegmat.com/all-my-probl ... 81383.html
https://www.beatthegmat.com/rounding-nee ... 57876.html
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

GMAT/MBA Expert

User avatar
GMAT Instructor
Posts: 8086
Joined: Sat Apr 25, 2015 10:56 am
Location: Los Angeles, CA
Thanked: 43 times
Followed by:29 members
ProGMAT wrote:
Fri Aug 16, 2013 12:47 am
If d = 2.0453 and d* is the decimal obtained by rounding d to the nearest hundredth, what is the value of d* - d ?
(A) -0.0053
(8) -0.0003
(C) 0.0007
(D) 0.0047
(E) 0.0153
Solution:

We see that d* = 2.05, which is the value of d when rounded to the nearest hundredth. Therefore, d* - d = 2.05 - 2.0453 = 0.0047.

Answer: D

Scott Woodbury-Stewart
Founder and CEO
[email protected]

Image

See why Target Test Prep is rated 5 out of 5 stars on BEAT the GMAT. Read our reviews

ImageImage