Author 
Message 
TAGS:

Hide Tags

Suspended Member
Joined: 23 Jul 2009
Posts: 58

How many odd threedigit integers greater than 800 are there [#permalink]
Show Tags
21 Aug 2009, 05:07
Question Stats:
62% (01:42) correct 38% (02:00) wrong based on 135 sessions
HideShow timer Statistics
How many odd threedigit integers greater than 800 are there such that all their digits are different? A. 40 B. 60 C. 72 D. 81 E. 104 If the number begins with 8, there are possibilities (5 possibilities for the last digit and 8 possibilities for the middle digit). If the number begins with 9, there are possibilities (4 possibilities for the last digit and 8 possibilities for the middle digit). In all, there are numbers that satisfy the constraints.
The correct answer is C.
GMAC25 : i think there are 9 possiblities for middle digit, 09 and excluding 8, now how can we say that there are 5 possibilties for last digit when middle digit is 1 then possible last digit values are 3,5,7,9.
i am not able to understand this.
Official Answer and Stats are available only to registered users. Register/ Login.



Suspended Member
Joined: 23 Jul 2009
Posts: 58

Re: GMAT CLUB tests  p&c problem [#permalink]
Show Tags
21 Aug 2009, 05:14
Please explain the solution!! I am weak in P&C



Director
Joined: 01 Apr 2008
Posts: 829
Name: Ronak Amin
Schools: IIM Lucknow (IPMX)  Class of 2014

Re: GMAT CLUB tests  p&c problem [#permalink]
Show Tags
21 Aug 2009, 05:27
Last digit is always ODD: case1: first digit is 8, then last digit has 5 options(1,3,5,7,9) and middle digit has 8 options as we have already chosen two digits for the first and the last positions. total numbers = 1*8*5 = 40
case2: first digit is 9, then last digit has 4 options(1,3,5,7) and middle digit has 8 options again. total numbers = 1*8*4 = 32 Ans:72
NOTE: last digit should always be one of 1,3,5,7,9



Suspended Member
Joined: 23 Jul 2009
Posts: 58

Re: GMAT CLUB tests  p&c problem [#permalink]
Show Tags
21 Aug 2009, 12:53
thanks a lot .... this solution cleared my doubt.



Founder
Joined: 04 Dec 2002
Posts: 16980
Location: United States (WA)

Re: GMAT CLUB tests  p&c problem [#permalink]
Show Tags
21 Aug 2009, 12:59
Also here: m2576554.htmlSee this post for a listing of all discussions: gmatclubtestsmasterthreadsalltests78599.html
_________________
Founder of GMAT Club
Just starting out with GMAT? Start here... or use our Daily Study Plan
Coauthor of the GMAT Club tests



Senior Manager
Joined: 18 Aug 2009
Posts: 385
Schools: UT at Austin, Indiana State University, UC at Berkeley
WE 1: 5.5
WE 2: 5.5
WE 3: 6.0

Re: GMAT CLUB tests  p&c problem [#permalink]
Show Tags
07 Sep 2010, 18:02
Thank you for explanation. It is very helpful!
_________________
Never give up,,,



Math Expert
Joined: 02 Sep 2009
Posts: 46207

Re: GMAT CLUB tests  p&c problem [#permalink]
Show Tags
11 Sep 2010, 22:51
How many odd threedigit integers greater than 800 are there such that all their digits are different?A. 40 B. 60 C. 72 D. 81 E. 104 In the range 800  900:1 choice for the first digit: 8; 5 choices for the third digit: 1, 3, 5, 7, 9; 8 choices for the second digit: 10 digits  first digit  third digit = 8 digits. 1*5*8 = 40. In the range 900  999:1 choice for the first digit: 9; 4 choices for the third digit: 1, 3, 5, 7 (9 is out as it's first digit); 8 choices for the second digit: 10 digits  first digit  third digit = 8 digits. 1*4*8 = 32. Total: 40+32 = 72. Answer: C. Also discussed at: odd3digitintegers94655.html and noproperties71853.html?hilit=range%20choice%20first%20digitHope it helps.
_________________
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? Extrahard Quant Tests with Brilliant Analytics



NonHuman User
Joined: 09 Sep 2013
Posts: 7007

Re: How many odd threedigit integers greater than 800 are there [#permalink]
Show Tags
22 May 2017, 21:54
Hello from the GMAT Club BumpBot! Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up  doing my job. I think you may find it valuable (esp those replies with Kudos). Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
_________________
GMAT Books  GMAT Club Tests  Best Prices on GMAT Courses  GMAT Mobile App  Math Resources  Verbal Resources




Re: How many odd threedigit integers greater than 800 are there
[#permalink]
22 May 2017, 21:54






