Bunuel wrote:

zisis wrote:

Josh has to run an electrical wire from point a to point b along a circuit that is restricted to the grid shown to the left. How many possible paths could Josh use that have the minimum possible length?

A 8

B 10

C 12

D 15

E 16

obv the answer can be found by counting the routes, but is there a better way?

You can notice that in order the length to be minimum wire should only go UP and RIGHT: namely twice UP and 4 times RIGHT.

So combination of UURRRR: # of permutations of 6 letters out of which there are 2 identical U's and 4 identical R's is \(\frac{6!}{2!4!}=15\).

Answer: D.

Hope it's clear.

thanks! thats exactly what i was looking for ! If i recall correcty, you must be the GMATclub combinations expert

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IDEA

how about we have experts stamps for certain individuals !

SC, combinations, RC, algebra etc....something the forum admins should consider...]