og 11ed problem

badri077 · Posted: Mon Aug 13, 2007 11:11 pm Post subject: og 11ed problem

is there a really fast way of solving PS problem #195 from OG 11ed ?
pat walks from intersection X to intersection Y problem ?

Thnx,
-Badri

beny · Posted: Tue Aug 14, 2007 12:06 am Post subject:

No one is going to look up the question to help you. If you want help, at least be active enough to type out the question.

gabriel · Posted: Tue Aug 14, 2007 12:41 am Post subject:

..Seriously dude .. the least u can do is type out the question .. plz do not expect people to go and fetch the question for u and then respond to your queries ..

givemeanid · Posted: Tue Aug 14, 2007 5:26 am Post subject:

Yeah. And do not even get me started on ones who post screen shots for problems with plain text...

badri077 · Posted: Tue Aug 14, 2007 8:22 am Post subject: reg: problem

sorry folks. the problem had a figure which I couldn't draw very easily. Hence the pointer to the problem.
Will write up the whole problem and try to draw the figure once I get home tonight.

-B
P.S. From what I remember-
imagine a 1st quadrant grid. How many different shortest paths are possible from (0,0) to (3,4) travelling only along the grid lines (going from y=0 to y=4, x=0 to x=3
I'll confirm this evening.

beny · Posted: Tue Aug 14, 2007 12:19 pm Post subject:

I remember this question... I believe the answer was 10?

By taking the shortest route possible, he can only travel Up (U) three or Right (R) two.

The combinations are:

UUURR
UURRU
URRUU
RRUUU
UURUR
URURU
RURUU
URUUR
RUURU
RUUUR

In other words:

5!/3!*2!

800GMAT · Posted: Thu Aug 16, 2007 3:31 pm Post subject:

here..lemme post the question

800GMAT · Posted: Thu Aug 16, 2007 3:36 pm Post subject:

beny, one question----what does 5! denote...........

beny · Posted: Thu Aug 16, 2007 5:46 pm Post subject:

The combinatoric way to solve this question is the "anagram approach". In other words, how many words can you make with a set of letters via rearranging the letters. The way to figure this out is:

(Total number of letters)! / (Number of each repeating letter)!

Here, the total number of letters is 5, there are 2 repeating R's and 3 repeating U's.

800GMAT · Posted: Fri Aug 17, 2007 8:03 am Post subject:

got it.....thnkx
Smile

Guest · Posted: Fri Aug 17, 2007 10:54 am Post subject:

What if the question asked, what are total number of ways from X to Y... Confused