NEW HERE? LEARN MORE
closeclose
Last visit was: 25 Apr 2024, 02:16 It is currently 25 Apr 2024, 02:16
Decision Tracker
My Rewards
New posts
New comers' posts

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.
Go to My Error Log Learn more
Close
Request Expert Reply
Confirm Cancel

What is the unit digit of x^3? (1) x is even (2) x^3 is between 10 and

SORT BY:
Date
Kudos
Tags:
Find Similar Topics 
Show Tags
Hide Tags
avatar
S
OhMy
Intern
Intern
Joined: 11 Feb 2018
Status:resting for now
Posts: 47
Own Kudos [?]: 103 [3]
Given Kudos: 126
Location: Germany
Concentration: Technology, Strategy
Send PM
Reviews Badge
What is the unit digit of x^3? (1) x is even (2) x^3 is between 10 and [#permalink] New post   20 Feb 2020, 15:56
3
Bookmarks
00:00
A
B
C
D
E

Difficulty:

35% (medium)

Question Stats:

70% (01:12) correct 30% (01:00) wrong based on 37 sessions
Hide Show timer Statistics
What is the units digit of \(x^3\)?

(1) x is even

(2) \(x^3\) is between 10 and 100
ShowHide Answer
Official Answer
C
User avatar
L
shameekv1989
Director
Director
Joined: 14 Dec 2019
Posts: 829
Own Kudos [?]: 888 [1]
Given Kudos: 354
Location: Poland
Concentration: Entrepreneurship, Strategy
Schools: Cambridge '22 (D) WBS (A$) IIMA PGPX'22 (D) WHU MBA (WD) ISB'22 (D)
GMAT 1: 640 Q49 V27
GMAT 2: 660 Q49 V31
GMAT 3: 720 Q50 V38
GPA: 4
WE:Engineering (Consumer Electronics)
Send PM
GMAT ToolKit User Reviews Badge
Re: What is the unit digit of x^3? (1) x is even (2) x^3 is between 10 and [#permalink] New post   20 Feb 2020, 16:31
1
Kudos
OhMy wrote:
What is the units digit of \(x^3\)?

(1) x is even

(2) \(x^3\) is between 10 and 100


OhMy :- Can you please explain how B could be an answer?

i) x is even -> x could be 2,4 -> x^3 = 8, 64 - Multiple values - Not Sufficient

ii) x^3 is between 10 and 100 -> x could be 3 or 4 -> x^3 can be 27 or 64 -> Units digit can be 7 or 4 - Insufficient

Combining i) and ii) x^3 can only be 64 -> Units digit is 4

Hence C should be an answer.
User avatar
L
Bunuel
Math Expert
Joined: 02 Sep 2009
Posts: 92912
Own Kudos [?]: 618882 [0]
Given Kudos: 81595
Send PM
CAT Tests Forum Quiz Mode
Re: What is the unit digit of x^3? (1) x is even (2) x^3 is between 10 and [#permalink] New post   21 Feb 2020, 00:11
Expert Reply
shameekv1989 wrote:
OhMy wrote:
What is the units digit of \(x^3\)?

(1) x is even

(2) \(x^3\) is between 10 and 100


OhMy :- Can you please explain how B could be an answer?

i) x is even -> x could be 2,4 -> x^3 = 8, 64 - Multiple values - Not Sufficient

ii) x^3 is between 10 and 100 -> x could be 3 or 4 -> x^3 can be 27 or 64 -> Units digit can be 7 or 4 - Insufficient

Combining i) and ii) x^3 can only be 64 -> Units digit is 4

Hence C should be an answer.


Edited the OA. It's C, not B.
avatar
S
OhMy
Intern
Intern
Joined: 11 Feb 2018
Status:resting for now
Posts: 47
Own Kudos [?]: 103 [0]
Given Kudos: 126
Location: Germany
Concentration: Technology, Strategy
Send PM
Reviews Badge
Re: What is the unit digit of x^3? (1) x is even (2) x^3 is between 10 and [#permalink] New post   21 Feb 2020, 05:40
shameekv1989 Bunuel

You are right guys. sorry, my mistake.
User avatar
L
EgmatQuantExpert
e-GMAT Representative
Joined: 04 Jan 2015
Posts: 3726
Own Kudos [?]: 16833 [0]
Given Kudos: 165
Send PM
Re: What is the unit digit of x^3? (1) x is even (2) x^3 is between 10 and [#permalink] New post   21 Feb 2020, 10:59
Expert Reply

Solution



To find
We need to determine
    • The units digit of \(x^3\)

Analysing Statement 1
As per the information given in statement 1, x is even
However, from this information, we cannot determine the exact units digit of x.
    • For example, if x = 2, then units digits of \(x^3\) is 8
    • Alternatively, if x = 4, then units digit of \(x^3\) is 4

Hence, statement 1 is not sufficient to answer the question.

Analysing Statement 2
As per the information given in statement 2, \(x^3\) is between 10 and 100
Hence, value of \(x^3\) can be either 27 or 64 – but we cannot uniquely determine the exact value of \(x^3\)

Hence, statement 2 is not sufficient to answer the question.

Combining Both Statements Together
We know \(x^3\) can be either 27 and 64, and x is also even (means \(x^3\) is even)
    • Hence, \(x^3\) is equal to 64 only, and units digit is 4

Thus, option C is the correct answer.

Correct Answer: Option C
avatar
G
fireagablast
Senior Manager
Senior Manager
Joined: 30 Jun 2019
Posts: 275
Own Kudos [?]: 89 [1]
Given Kudos: 8
Send PM
Re: What is the unit digit of x^3? (1) x is even (2) x^3 is between 10 and [#permalink] New post   21 Feb 2020, 19:07
1
Kudos
Why is the answer C and not E? It never says that X is an integer. Unless we are to assume that by definition the word "even" implicitly refers to integers.

(2.66)^3 = 18.821. This is an "even" decimal value for instance, but isn't an integer.
GMAT Club Bot
gmatclubot
Re: What is the unit digit of x^3? (1) x is even (2) x^3 is between 10 and [#permalink]
21 Feb 2020, 19:07
Moderator:
Bunuel
Math Expert
92904 posts

Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne
Main navigation
GMAT Resources
Partners
MBA Resources
www.gmac.com|www.mba.com | | GMAT Club Rules | Terms and Conditions