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

It is currently 15 Nov 2018, 11:03

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 in November
PrevNext
SuMoTuWeThFrSa
28293031123
45678910
11121314151617
18192021222324
2526272829301
Open Detailed Calendar
  • Free GMAT Strategy Webinar

     November 17, 2018

     November 17, 2018

     07:00 AM PST

     09:00 AM PST

    Nov. 17, 7 AM PST. Aiming to score 760+? Attend this FREE session to learn how to Define your GMAT Strategy, Create your Study Plan and Master the Core Skills to excel on the GMAT.
  • GMATbuster's Weekly GMAT Quant Quiz # 9

     November 17, 2018

     November 17, 2018

     09:00 AM PST

     11:00 AM PST

    Join the Quiz Saturday November 17th, 9 AM PST. The Quiz will last approximately 2 hours. Make sure you are on time or you will be at a disadvantage.

If a number N is chosen at random from the set of two-digit integers

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

Hide Tags

Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 50613
If a number N is chosen at random from the set of two-digit integers  [#permalink]

Show Tags

New post 22 Jul 2018, 22:13
00:00
A
B
C
D
E

Difficulty:

  65% (hard)

Question Stats:

45% (01:42) correct 55% (01:46) wrong based on 74 sessions

HideShow timer Statistics

If a number N is chosen at random from the set of two-digit integers whose digits are both prime numbers, what is the probability that N is divisible by 3?

A. 1/3
B. 1/4
C. 9/25
D. 5/16
E. 0

_________________

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

Manager
Manager
User avatar
S
Joined: 21 Dec 2014
Posts: 66
Location: Viet Nam
Concentration: Entrepreneurship, General Management
Schools: Duke '21
GMAT 1: 710 Q49 V37
GPA: 3.8
WE: Other (Other)
GMAT ToolKit User Reviews Badge
If a number N is chosen at random from the set of two-digit integers  [#permalink]

Show Tags

New post Updated on: 22 Jul 2018, 22:40
Bunuel wrote:
If a number N is chosen at random from the set of two-digit integers whose digits are both prime numbers, what is the probability that N is divisible by 3?

A. 1/3
B. 1/4
C. 9/25
D. 5/16
E. 0


Prime number: 2,3,5,7
number of 2 digit integers whose digit are both prime: 4A2=12 number
number in set divisible by 3: 27,72, 57,75; 4 number
Probability that N is divisible by 7: 4/12=1/3
assuming 2 number is different=>wrong answer
_________________

Kudo is nothing but encouragement!


Originally posted by LeoGT on 22 Jul 2018, 22:28.
Last edited by LeoGT on 22 Jul 2018, 22:40, edited 1 time in total.
Senior PS Moderator
User avatar
V
Joined: 26 Feb 2016
Posts: 3307
Location: India
GPA: 3.12
Premium Member CAT Tests
Re: If a number N is chosen at random from the set of two-digit integers  [#permalink]

Show Tags

New post 22 Jul 2018, 22:28
3
Bunuel wrote:
If a number N is chosen at random from the set of two-digit integers whose digits are both prime numbers, what is the probability that N is divisible by 3?

A. 1/3
B. 1/4
C. 9/25
D. 5/16
E. 0


The 4 digits which are prime numbers are 2,3,5, or 7. N can have 16(4*4) possibilities.

For any number with 2 digits, the sum of the 2 digits must be divisible by 3.

There are 2 possibilities for the 2-digit number to be divisible by 3
1. When digits differ - (2,7) and (5,7) - 4 such numbers | 2. Same digit - (3,3) - 1 such number

Therefore, the probability that N is divisible by 3 is \(\frac{5}{16}\)(Option D)
_________________

You've got what it takes, but it will take everything you've got

Intern
Intern
avatar
B
Joined: 11 Jun 2015
Posts: 19
Location: Iran (Islamic Republic of)
Concentration: Accounting, Finance
WE: Education (Education)
GMAT ToolKit User CAT Tests
Re: If a number N is chosen at random from the set of two-digit integers  [#permalink]

Show Tags

New post 23 Jul 2018, 00:17
N=_ _
there are 4 prime numbers less than 10: 2,3,5,7
therefore the total events equal 4*4=16
to be divisible by 3, sum of the digits of the number must be divisible by 3.
2+7=9
3+3=6
5+7=12
7+2=9
7+5=12

p=5/16
option D
GMAT Club Bot
Re: If a number N is chosen at random from the set of two-digit integers &nbs [#permalink] 23 Jul 2018, 00:17
Display posts from previous: Sort by

If a number N is chosen at random from the set of two-digit integers

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


Copyright

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®.