[AnnieMei]

I love puzzles. Here;s one my 13 year old cousing gave me.



I think the instructions for this got kinda muddled, so here is he puzzle as how its presented:


a ________________________

I_______I________I_______I

I_______I________I_______I

I_______I________I_______b

Imagine that this is 9 square city blocks. You have to get from point (a) to point (b). How many possible routes can you take. Be aware you cannot back track, you must have foward progression towards point (b) at all times.

So dont backtrack (meaning once you go one direction, you cant go the opposite)

 

[XL1200C]

I'm my half asleep state, I'll say 12? Even though I know it'll be more than that....

 

[firefighter81]

I count 6, probably way off, it's 6AM here and I'm just getting off work.

 

[evils-03-RR]

0 road a doesnt connect.

 

[slo_tom]

64? BLeh .

 

[Gimpdiggity]

0 road a doesnt connect.

I think it's supppsed to connect. How do you suggest he draw the picture better?

 

[Gimpdiggity]

There are a TON of them.

 

[AnnieMei]

No one? Hmm. I think we need to have some 13 yr olds kick out butts on this...

 

[yellowduc]

needs more rules, i know you said you can't back track, but if you were to go right and then take your first right, can you then take a right again or is that considered back-tracking? I had a math course where you solve these things, discrete math. On the first day we did the problem from Good Will Hunting, the one with the dots. The teacher explained that because no one ever sees abstract math they thought it was hard, it took like five minutes to explain. Granted, on the first day of class, I couldn't have done it but at the end I could.
I think the answer is 24, you can go in two directions from 9 intersections but only one direction from 6 intersections (the far right and the bottom intersections). That is only considering that there is no back-tracking at all. I may be totally wrong as it has been a while since I had the class.

 

[AnnieMei]

You can only move in one direction. Back tracking is if you go back the way you had come (ie if you across to the right, you can't go down then come back to the left)

The answer btw is 20.
Go ahead and draw it out.


Reasons found here:
http://www.successlink.org/great/g222.html