Last visit was: 12 May 2026, 14:07 It is currently 12 May 2026, 14:07
Close
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
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.
Close
Request Expert Reply
Confirm Cancel
User avatar
Bunuel
User avatar
Math Expert
Joined: 02 Sep 2009
Last visit: 12 May 2026
Posts: 110,299
Own Kudos:
Given Kudos: 106,204
Products:
Expert
Expert reply
Active GMAT Club Expert! Tag them with @ followed by their username for a faster response.
Posts: 110,299
Kudos: 814,551
 [10]
2
Kudos
Add Kudos
8
Bookmarks
Bookmark this Post
Most Helpful Reply
User avatar
Bunuel
User avatar
Math Expert
Joined: 02 Sep 2009
Last visit: 12 May 2026
Posts: 110,299
Own Kudos:
814,551
 [7]
Given Kudos: 106,204
Products:
Expert
Expert reply
Active GMAT Club Expert! Tag them with @ followed by their username for a faster response.
Posts: 110,299
Kudos: 814,551
 [7]
4
Kudos
Add Kudos
3
Bookmarks
Bookmark this Post
General Discussion
avatar
chaitalip
Joined: 01 Jul 2017
Last visit: 08 Oct 2020
Posts: 4
Own Kudos:
Given Kudos: 168
Posts: 4
Kudos: 4
Kudos
Add Kudos
Bookmarks
Bookmark this Post
avatar
manishtank1988
Joined: 14 Oct 2012
Last visit: 31 Oct 2019
Posts: 112
Own Kudos:
Given Kudos: 1,023
Products:
Posts: 112
Kudos: 287
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Bunuel
Official Solution:


If \(x\) is the tenths digit in the decimal \(9.x5\), what is the value of \(x\)?

(1) When \(15 - 9.x5\) is rounded to the nearest tenth, the result is \(5.4\).

This implies that \(15 - 9.x5\) must be between \(5.35\) (inclusive) and \(5.45\) (not inclusive). Any number from this range when rounded to the nearest tenth will be \(5.4\). So, we can write the following inequality:

\(5.35 \leq (15 - 9.x5) < 5.45\);

Subtract 15 from all parts: \(-9.65 \leq -9.x5 < -9.55\);

Multiply by -1 and flip the signs: \(9.65 \geq 9.x5 > 9.55\), which is the same as \(9.55 < 9.x5 \leq 9.65\). From this we can deduce that \(x\) can be only \(6\). Sufficient.

(2) When \(9.x5 – 5\) is rounded to the nearest tenth, the result is \(4.7\).

This implies that \(9.x5 – 5\) must be between \(4.65\) (inclusive) and \(4.75\) (not inclusive). Any number from this range when rounded to the nearest tenth will be \(4.7\). So, we can write the following inequality:

\(4.65 \leq (9.x5 – 5) < 4.75\);

Add 5 to all parts: \(9.65 \leq 9.x5 < 9.75\). From this we can deduce that \(x\) can be only \(6\). Sufficient.


Answer: D


Hello Bunuel
Can you please explain/elaborate as to how you arrived at highlighted statements?
Thanks

This is what i did -
1)
15.00
- 9.x5
5.y5 = 5.4
y = [9 - (x+1)] ; (x+1) because we have 5.x5 ~ 5.4. So whatever value we get would be +1 because of 0.05 - i hope i am clarifying myself....

9 - x - 1 = 4
8 - x = 4
x = 4

2)
9.x5
- 5.00
4.y5 ~ 4.7
y = x+1 = 7
x = 6

Thus D
Please let me know how did you arrived at highlighted portion and what i did was wrong?
Thanks
User avatar
Bunuel
User avatar
Math Expert
Joined: 02 Sep 2009
Last visit: 12 May 2026
Posts: 110,299
Own Kudos:
Given Kudos: 106,204
Products:
Expert
Expert reply
Active GMAT Club Expert! Tag them with @ followed by their username for a faster response.
Posts: 110,299
Kudos: 814,551
Kudos
Add Kudos
Bookmarks
Bookmark this Post
manishtank1988
Bunuel
Official Solution:


If \(x\) is the tenths digit in the decimal \(9.x5\), what is the value of \(x\)?

(1) When \(15 - 9.x5\) is rounded to the nearest tenth, the result is \(5.4\).

This implies that \(15 - 9.x5\) must be between \(5.35\) (inclusive) and \(5.45\) (not inclusive). Any number from this range when rounded to the nearest tenth will be \(5.4\). So, we can write the following inequality:

\(5.35 \leq (15 - 9.x5) < 5.45\);

Subtract 15 from all parts: \(-9.65 \leq -9.x5 < -9.55\);

Multiply by -1 and flip the signs: \(9.65 \geq 9.x5 > 9.55\), which is the same as \(9.55 < 9.x5 \leq 9.65\). From this we can deduce that \(x\) can be only \(6\). Sufficient.

(2) When \(9.x5 – 5\) is rounded to the nearest tenth, the result is \(4.7\).

This implies that \(9.x5 – 5\) must be between \(4.65\) (inclusive) and \(4.75\) (not inclusive). Any number from this range when rounded to the nearest tenth will be \(4.7\). So, we can write the following inequality:

\(4.65 \leq (9.x5 – 5) < 4.75\);

Add 5 to all parts: \(9.65 \leq 9.x5 < 9.75\). From this we can deduce that \(x\) can be only \(6\). Sufficient.


Answer: D


Hello Bunuel
Can you please explain/elaborate as to how you arrived at highlighted statements?
Thanks

This is what i did -
1)
15.00
- 9.x5
5.y5 = 5.4
y = [9 - (x+1)] ; (x+1) because we have 5.x5 ~ 5.4. So whatever value we get would be +1 because of 0.05 - i hope i am clarifying myself....

9 - x - 1 = 4
8 - x = 4
x = 4

2)
9.x5
- 5.00
4.y5 ~ 4.7
y = x+1 = 7
x = 6

Thus D
Please let me know how did you arrived at highlighted portion and what i did was wrong?
Thanks

Take any number from that range, round it to the nearest tenth and you will be \(5.4\).
User avatar
norovers
Joined: 20 Apr 2018
Last visit: 02 Sep 2020
Posts: 24
Own Kudos:
Given Kudos: 52
Location: United States (DC)
GPA: 3.84
Products:
Posts: 24
Kudos: 10
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Hi Bunuel

I am a bit confused by this explanation. Is there any easier way to deduce this?

I just assumed D because if we know that the hundredths digit ends in a five, then we know we must round the tenth digit up. Thus, we should be able to determine the tenths digit as a result. Is my logic flawed?

Thanks in advance for your help.
User avatar
Bunuel
User avatar
Math Expert
Joined: 02 Sep 2009
Last visit: 12 May 2026
Posts: 110,299
Own Kudos:
814,551
 [1]
Given Kudos: 106,204
Products:
Expert
Expert reply
Active GMAT Club Expert! Tag them with @ followed by their username for a faster response.
Posts: 110,299
Kudos: 814,551
 [1]
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
norovers
Hi Bunuel

I am a bit confused by this explanation. Is there any easier way to deduce this?

I just assumed D because if we know that the hundredths digit ends in a five, then we know we must round the tenth digit up. Thus, we should be able to determine the tenths digit as a result. Is my logic flawed?

Thanks in advance for your help.

This is a tough question and does not have a silver bullet solution. You can check alternative solutions here: https://gmatclub.com/forum/if-x-represe ... 43252.html

Hope it helps.
User avatar
norovers
Joined: 20 Apr 2018
Last visit: 02 Sep 2020
Posts: 24
Own Kudos:
Given Kudos: 52
Location: United States (DC)
GPA: 3.84
Products:
Posts: 24
Kudos: 10
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Thanks Bunuel! I think the first response is a very helpful way to go about it.
User avatar
harsh8686
Joined: 19 Feb 2018
Last visit: 23 Feb 2024
Posts: 97
Own Kudos:
Given Kudos: 228
GMAT 1: 530 Q48 V15
GMAT 2: 640 Q48 V30
GMAT 3: 590 Q46 V25
GMAT 4: 600 Q48 V25 (Online)
GMAT 5: 710 Q49 V37
GMAT 5: 710 Q49 V37
Posts: 97
Kudos: 166
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Bunuel
manishtank1988
Bunuel
Official Solution:

This implies that \(15 - 9.x5\) must be between \(5.35\) (inclusive) and \(5.45\) (not inclusive). Any number from this range when rounded to the nearest tenth will be \(5.4\). So, we can write the following inequality:


Hi Bunuel, can you please help me with the reason for inclusion and exclusion.
thanks.
User avatar
Bunuel
User avatar
Math Expert
Joined: 02 Sep 2009
Last visit: 12 May 2026
Posts: 110,299
Own Kudos:
Given Kudos: 106,204
Products:
Expert
Expert reply
Active GMAT Club Expert! Tag them with @ followed by their username for a faster response.
Posts: 110,299
Kudos: 814,551
Kudos
Add Kudos
Bookmarks
Bookmark this Post
harsh8686
Bunuel
Official Solution:

This implies that \(15 - 9.x5\) must be between \(5.35\) (inclusive) and \(5.45\) (not inclusive). Any number from this range when rounded to the nearest tenth will be \(5.4\). So, we can write the following inequality:


Hi Bunuel, can you please help me with the reason for inclusion and exclusion.
thanks.

5.35 rounded to the nearest tenth is 5.4 but 5.45 rounded to the nearest tenth is 5.5.

Rounding is simplifying a number to a certain place value. To round the decimal drop the extra decimal places, and if the first dropped digit is 5 or greater, ROUND UP the last digit that you keep. If the first dropped digit is 4 or smaller, ROUND DOWN (keep the same) the last digit that you keep.

Example:
5.3485 rounded to the nearest tenth = 5.3, since the dropped 4 is less than 5.
5.3485 rounded to the nearest hundredth = 5.35, since the dropped 8 is greater than 5.
5.3485 rounded to the nearest thousandth = 5.349, since the dropped 5 is equal to 5.

So, according to the above 8.35y rounded to the nearest tenth will be 8.4 irrespective of the value of y.

For mote on this check the following posts:
Math: Number Theory
Rounding Rules on the GMAT: Slip to the Side and Look for a Five!

3. Fractions, Decimals, Ratios and Proportions



For more:
ALL YOU NEED FOR QUANT ! ! !
Ultimate GMAT Quantitative Megathread


Hope it helps.
Moderators:
Math Expert
110299 posts
Founder
43270 posts