It is currently 22 Feb 2018, 05:00

TODAY:

MIT Sloan Releasing 1st Wave of Interview Invites - Join GMATClub CHAT for Live Updates


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

A company will create different ID numbers for its employees. Senior

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

Hide Tags

Expert Post
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 43864
A company will create different ID numbers for its employees. Senior [#permalink]

Show Tags

New post 29 Jan 2018, 04:51
Expert's post
1
This post was
BOOKMARKED
00:00
A
B
C
D
E

Difficulty:

  25% (medium)

Question Stats:

100% (01:01) correct 0% (00:00) wrong based on 26 sessions

HideShow timer Statistics

A company will create different ID numbers for its employees. Senior-level employees will receive 4-digit ID numbers, and junior level employees will receive 5-digit ID numbers. If the first digit of any ID number cannot be zero, and if no digits will be repeated in any ID number, what is the ratio of the total number of senior level ID numbers possible to the total number of junior level ID numbers possible?

A. 1/12
B. 1/6
C. 1/4
D. 1/3
E. 1/2
[Reveal] Spoiler: OA

_________________

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

BSchool Forum Moderator
User avatar
V
Joined: 26 Feb 2016
Posts: 2063
Location: India
GPA: 3.12
Premium Member CAT Tests
Re: A company will create different ID numbers for its employees. Senior [#permalink]

Show Tags

New post 29 Jan 2018, 05:40
Bunuel wrote:
A company will create different ID numbers for its employees. Senior-level employees will receive 4-digit ID numbers, and junior level employees will receive 5-digit ID numbers. If the first digit of any ID number cannot be zero, and if no digits will be repeated in any ID number, what is the ratio of the total number of senior level ID numbers possible to the total number of junior level ID numbers possible?

A. 1/12
B. 1/6
C. 1/4
D. 1/3
E. 1/2


When we read this question, the important takeaway are

1. The first digit of any ID number will not be 0.
2. Every Senior-level employee will have a 4-digit ID number
3. Every Junior-level employee will have a 5-digit ID number
4. No digits can be repeated in any employee's ID number

The total number of Senior-Level employees possible is 9*9*8*7
Similarly, the total number of Junior-Level employees possible is 9*9*8*7*6

Hence, the ratio of Senior-level employee ID's to Junior-level employee ID's is \(\frac{9*9*8*7}{9*9*8*7*6} = \frac{1}{6}\) (Option B)
_________________

Stay hungry, Stay foolish

2017-2018 MBA Deadlines

Class of 2020: Rotman Thread | Schulich Thread
Class of 2019: Sauder Thread

Intern
Intern
avatar
B
Joined: 28 Jul 2016
Posts: 14
Location: India
GMAT 1: 680 Q50 V32
GPA: 3.97
Re: A company will create different ID numbers for its employees. Senior [#permalink]

Show Tags

New post 29 Jan 2018, 10:08
Ratio = total ways to form ID for seniors/ total ways to form ID for junior
= 9*9*8*7/9*9*8*7*6
=1/6
Hence B
Expert Post
Target Test Prep Representative
User avatar
S
Status: Head GMAT Instructor
Affiliations: Target Test Prep
Joined: 04 Mar 2011
Posts: 1986
Re: A company will create different ID numbers for its employees. Senior [#permalink]

Show Tags

New post 30 Jan 2018, 10:15
Bunuel wrote:
A company will create different ID numbers for its employees. Senior-level employees will receive 4-digit ID numbers, and junior level employees will receive 5-digit ID numbers. If the first digit of any ID number cannot be zero, and if no digits will be repeated in any ID number, what is the ratio of the total number of senior level ID numbers possible to the total number of junior level ID numbers possible?

A. 1/12
B. 1/6
C. 1/4
D. 1/3
E. 1/2


The first digit of a senior-level ID number can be any of the 9 digits 1-9, inclusive (can’t be zero). The second digit can be any of the 10 digits (0-9, inclusive), but it can’t be a repeat of the previous digit. Thus, there are 9 possibilities. The third digit can not repeat either of the two previous digits, so there are only 8 possibilities. The fourth digit cannot repeat any of the previous digits, so there are 7 possibilities. Thus, we have a total of 9 x 9 x 8 x 7 possible senior-level IDs.

Determination of the possible number of junior-level IDs is identical to the process for senior-level IDs, except there are 5 numbers in the junior-level ID: 9 x 9 x 8 x 7 x 6 possibilities.

Thus, the ratio of the number of senior level IDs to junior level IDs is:

(9 x 9 x 8 x 7)/(9 x 9 x 8 x 7 x 6) = 1/6

Answer: B
_________________

Jeffery Miller
Head of GMAT Instruction

GMAT Quant Self-Study Course
500+ lessons 3000+ practice problems 800+ HD solutions

Re: A company will create different ID numbers for its employees. Senior   [#permalink] 30 Jan 2018, 10:15
Display posts from previous: Sort by

A company will create different ID numbers for its employees. Senior

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


GMAT Club MBA Forum Home| About| Terms and Conditions| 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®.