Thursday, August 27, 2009

Question of the day - 27th August, 2009

Question 1:

How many five-digit numbers are there, if the two leftmost digits are even, the other digits are odd and the digit 4 cannot appear more than once in the number?
a)1875
b)2000
c)2375
d)2500
e)3875

Question 2:

6 persons seat themselves at round table. What is the probability that 2 given persons are adjacent?
(A) 1/5
(B) 2/5
(C) 1/10
(D) 1/7
(E) 2/15

OA will be posted soon.

Thanks,
Quant-Master
Posted by GMAT at 5:06 AM

4 comments:

  1. AnonymousAugust 27, 2009 at 12:47 PM

    Question1: B
    Question2: A

    ReplyDelete
  2. GMATAugust 30, 2009 at 7:45 PM

    Response to Question 1:

    Total number of ways of forming a 5 digit number with first 2 digits even and the next 3 odd is = 4*5*5*5*5 = 2500 --- 1

    Total number of ways of forming a 5 digit number with first two digits being 4 and the rest odd is = 1*1*5*5*5 = 125 --- 2

    (1)- (2) = 2375

    Response to Question 2:

    Since two given persons are always adjacent let's consider them as 1. Hence we have 5 people. 5 people can be arranged in a circle in (5-1)! ways Hence 4!*2! --- (1) (2 because two given person can change between themselves)

    Total ways of arranging 6 people in circle is 5!--- (2) Hence (1)/(2) = 2/5

    Let me know if you have any queries

    Thanks,
    Quant-Master

    ReplyDelete
  3. Mr MaltesersSeptember 2, 2009 at 5:01 AM

    ...fairly new to this coding...I don't follow the reasoning because I'm not aware of the symbology; what's "!" in front of a digit...and the brackets?

    Cheers

    ReplyDelete
  4. Rahil M ManiyarSeptember 9, 2009 at 11:00 AM

    HI Malsteers, ! means factorial of a number. For e.g.: 2! = 2*1 = 2, 3! = 3*2#1 = 6 and so on. And brackets are used to refer to that particular statement i.e., (1)/(2) is nothing but the result of statement 1 divided by that of statement 2.

    Thanks and regards,
    Rahil

    ReplyDelete

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