GMAT Question of the Day - Daily to your Mailbox; hard ones only

It is currently 20 Jun 2018, 21:54

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

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

What is the units digit of the number z?

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:

Hide Tags

5 KUDOS received
Manager
Manager
avatar
Joined: 06 Jun 2012
Posts: 135
GMAT ToolKit User
What is the units digit of the number z? [#permalink]

Show Tags

New post 05 Aug 2013, 05:23
5
7
00:00
A
B
C
D
E

Difficulty:

  45% (medium)

Question Stats:

46% (00:34) correct 54% (00:30) wrong based on 337 sessions

HideShow timer Statistics

What is the units digit of the number z?

(1) 17 < z < 20
(2) 18 < z < 21

_________________

Please give Kudos if you like the post

5 KUDOS received
VP
VP
User avatar
Status: Far, far away!
Joined: 02 Sep 2012
Posts: 1099
Location: Italy
Concentration: Finance, Entrepreneurship
GPA: 3.8
GMAT ToolKit User
Re: What is the units digit of the number z? [#permalink]

Show Tags

New post 05 Aug 2013, 05:26
5
1
What is the units digit of the number z?

1. 17 < z < 20
z=18 unit=8, z=19 unit=9.
Not sufficient

2. 18 < z < 21
z=19 unit=9, z=20 unit=0.
Not sufficient

(1+2)18<z<20
z=18.5 unit=8, z=19 unit=9.
Not sufficient (it does not say that z is a integer, so z can be a decimal as well).
_________________

It is beyond a doubt that all our knowledge that begins with experience.

Kant , Critique of Pure Reason

Tips and tricks: Inequalities , Mixture | Review: MGMAT workshop
Strategy: SmartGMAT v1.0 | Questions: Verbal challenge SC I-II- CR New SC set out !! , My Quant

Rules for Posting in the Verbal Forum - Rules for Posting in the Quant Forum[/size][/color][/b]

Director
Director
User avatar
Joined: 14 Dec 2012
Posts: 810
Location: India
Concentration: General Management, Operations
GMAT 1: 700 Q50 V34
GPA: 3.6
GMAT ToolKit User
Re: What is the units digit of the number z? [#permalink]

Show Tags

New post 05 Aug 2013, 07:52
summer101 wrote:
What is the units digit of the number z?

1. 17 < z < 20
2. 18 < z < 21


since we are not told that z is an integer hence it can be in decimal.

1. 17 < z < 20
it means:
z can be 17.01===18===18.01===19===19.99
hence possible answers are 7 or 8 or 9
not sufficient

2. 18 < z < 21
it means :
z can be 18.01===19===19.01===20===20.01===20.99
hence possible answers 8 or 9 or 0
not sufficient

combining both
18<z<20
z can be 18.01===19===19.01===19.99
hence possible answers 8 or 9
again not sufficient
not sufficient

hence E
_________________

When you want to succeed as bad as you want to breathe ...then you will be successfull....

GIVE VALUE TO OFFICIAL QUESTIONS...



GMAT RCs VOCABULARY LIST: http://gmatclub.com/forum/vocabulary-list-for-gmat-reading-comprehension-155228.html
learn AWA writing techniques while watching video : http://www.gmatprepnow.com/module/gmat-analytical-writing-assessment
: http://www.youtube.com/watch?v=APt9ITygGss

Senior Manager
Senior Manager
avatar
B
Joined: 24 Aug 2009
Posts: 481
Schools: Harvard, Columbia, Stern, Booth, LSB,
Re: What is the units digit of the number z? [#permalink]

Show Tags

New post 05 Aug 2013, 09:13
summer101 wrote:
What is the units digit of the number z?
1. 17 < z < 20
2. 18 < z < 21


Statement 1
z can be any number (including non-integer) between 17 & 20
Not sufficient

Statement 2
z can be any number (including non-integer) between 18 & 21
Not sufficient

Statement 1 & 2
z can be any number (including non-integer) between 18 & 20
If Z was integer, then option C would be sufficient but nowhere it is mentioned that z is an integer
Thus Not sufficient

Answer E
_________________

If you like my Question/Explanation or the contribution, Kindly appreciate by pressing KUDOS.
Kudos always maximizes GMATCLUB worth
-Game Theory

If you have any question regarding my post, kindly pm me or else I won't be able to reply

Manager
Manager
avatar
Joined: 25 Oct 2013
Posts: 160
Re: What is the units digit of the number z? [#permalink]

Show Tags

New post 08 Feb 2014, 07:22
The key here is identifying the fact that z CAN be a non-integer. hence E.

(1) 17<z<20
z can be 18 or 19 different units digit insufficient.
(2) 18<z<21
z =can be 19 or 20 different units digit insufficient.

(1)+(2)
18<z<20
z can be 18.7 or 19 or 19.8 again different units digit insufficient.
_________________

Click on Kudos if you liked the post!

Practice makes Perfect.

Senior SC Moderator
User avatar
V
Joined: 14 Nov 2016
Posts: 1294
Location: Malaysia
GMAT ToolKit User Premium Member CAT Tests
Re: What is the units digit of the number z? [#permalink]

Show Tags

New post 21 Mar 2017, 23:11
summer101 wrote:
What is the units digit of the number z?

(1) 17 < z < 20
(2) 18 < z < 21


OFFICIAL SOLUTION


Correct Answer: E

The units digit is the digit in the "ones" column; that is, it's the number directly to the left of the decimal point.

Statement 1 indicates tells us that the units digit is 8 or 9 because z could be the integers 18 or 19 and any associated mixed number- we don't know if z is an integer or not. Because we could arrive at multiple answers, this statement is insufficient.

Statement 2 indicates that z could be the integers 19 or 20 (or any associated mixed number), giving us the units digits 9 and 0, respectively. This statement is also insufficient. When taken together, the statements indicate that z must be between 18 and 20, but they do not specify that z must be an integer. For example, z could very well be 19, but it could be 18.5. Because we can still have two different units digits (8 and 9), the statements, even together, are insufficient, and the correct answer is E.
_________________

"Be challenged at EVERY MOMENT."

“Strength doesn’t come from what you can do. It comes from overcoming the things you once thought you couldn’t.”

"Each stage of the journey is crucial to attaining new heights of knowledge."

Rules for posting in verbal forum | Please DO NOT post short answer in your post!

Senior Manager
Senior Manager
avatar
B
Joined: 05 Jan 2017
Posts: 427
Location: India
Premium Member
Re: What is the units digit of the number z? [#permalink]

Show Tags

New post 22 Mar 2017, 02:58
summer101 wrote:
What is the units digit of the number z?

(1) 17 < z < 20
(2) 18 < z < 21


Z is an integer

St 1: the unit digit will be either 8 or 9. INSUFFICIENT

St 2: The unit digit will be either 9 or 0. INSUFFICIENT

ST 1 & ST 2: The unit digit will be 9. ANSWER

option C
Expert Post
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 46215
Re: What is the units digit of the number z? [#permalink]

Show Tags

New post 22 Mar 2017, 03:01
ByjusGMATapp wrote:
summer101 wrote:
What is the units digit of the number z?

(1) 17 < z < 20
(2) 18 < z < 21


Z is an integer

St 1: the unit digit will be either 8 or 9. INSUFFICIENT

St 2: The unit digit will be either 9 or 0. INSUFFICIENT

ST 1 & ST 2: The unit digit will be 9. ANSWER

option C


Please note that the correct answer to this question is E, not C. You can check the OA in the original post and solutions (including official one) above your post.
_________________

New to the Math Forum?
Please read this: Ultimate GMAT Quantitative Megathread | All You Need for Quant | PLEASE READ AND FOLLOW: 12 Rules for Posting!!!

Resources:
GMAT Math Book | Triangles | Polygons | Coordinate Geometry | Factorials | Circles | Number Theory | Remainders; 8. Overlapping Sets | PDF of Math Book; 10. Remainders | GMAT Prep Software Analysis | SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS) | Tricky questions from previous years.

Collection of Questions:
PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. ,11 Mixed Questions, 12 Fresh Meat

DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS; 9 Devil's Dozen!!!; 10 Number Properties set., 11 New DS set.


What are GMAT Club Tests?
Extra-hard Quant Tests with Brilliant Analytics

Re: What is the units digit of the number z?   [#permalink] 22 Mar 2017, 03:01
Display posts from previous: Sort by

What is the units digit of the number z?

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  


GMAT Club MBA Forum Home| About| Terms and Conditions and Privacy Policy| GMAT Club Rules| Contact| Sitemap

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®.