|
Author |
Message |
|
TAGS:
|
|
|
Manager
Joined: 07 Jun 2006
Posts: 113
Followers: 2
Kudos [?]:
2
[0], given: 0
|
There are 4 quarters and 3 dimes placed at random in a line. [#permalink]
 15 Oct 2006, 11:14
There are 4 quarters and 3 dimes placed at random in a line. The probability that the both extreme coins are dimes is
a) 1/4
b) 1/3
c) 1/7
d) 1/12
e) 1/2
|
|
|
|
|
|
|
Senior Manager
Joined: 08 Jun 2006
Posts: 347
Location: Washington DC
Followers: 1
Kudos [?]:
5
[0], given: 0
|
I think it is 1 / 7
Explanation –
4 quarters are identical and 3 dimes are identical
4 quarters and 3 dimes can be placed in (4 + 3) ! / ( 4! * 3 !) ways = 35 ways
Consider extreme 2 corners are 2 dimes. Then the remaining coins are 4 quarters and 1 dimes.
4 quarters and 1 dime can be arranged in (4 + 1) ! / ( 4! * 1 !) = 5
So the probability is = (Possible 5 cases) / (total cases 35) = 1/7
|
|
|
|
|
|
Manager
Joined: 01 Oct 2006
Posts: 246
Followers: 1
Kudos [?]:
4
[0], given: 0
|
Re: Quarters n Dimes [#permalink]
15 Oct 2006, 11:28
yeah, I also get 1/7.
|
|
|
|
|
|
Manager
Joined: 08 Jul 2006
Posts: 91
Followers: 1
Kudos [?]:
0
[0], given: 0
|
1/7 too
D _ _ _ _ _ D
3P2 * 5P5
------------
7P7
|
|
|
|
|
|
Senior Manager
Joined: 05 Oct 2006
Posts: 272
Followers: 1
Kudos [?]:
1
[0], given: 0
|
i think the qus is simply asking how to choose 2 quarters out of a total of 7 coins...and not about how other coins will be placed...
what u think??
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Similar topics |
Author |
Replies |
Last post |
|
Similar
Topics:
|
 |
|
|
Jill's pocket contains 3 quarters, 4 dimes, 2 nickels, and 6
|
Curly05 |
8 |
18 Jul 2003, 19:03 |
|
|
|
|
6 red blocks and 4 white blocks are placed at random in a
|
araspai |
7 |
09 Oct 2003, 21:45 |
|
|
|
 |
A nickel, a dime, and 2 identical quarters are arranged
|
marcodonzelli |
5 |
31 Jan 2008, 22:22 |
|
|
|
|
DIMES , QUARTERS
|
vcbabu |
2 |
27 Jun 2009, 21:29 |
|
|
|
|
A nickel, a dime, and 2 quarters are arranged along a side
|
krishnasty |
2 |
03 Nov 2010, 05:21 |
|
|
|
|
|
|
close
