Marvin the fly starts at $(0,0).$ Each step, Marvin moves one unit right or one unit up. He is trying to get to the point $(5,7)$. However, at $(4,3)$ there is a frog that will eat him if he goes through that point. In how many ways can Marvin reach $(5,7)$?

This problem is a bit different than the one web2.0calc.

I got 792- something. I can not find what to subtract from, also known as complementary counting btw

The answer is not 757.

Sarvajit May 21, 2020

edited by
Guest
May 21, 2020

edited by Guest May 21, 2020

edited by Guest May 21, 2020

#3**+1 **

Hi Sarvajit,

You're on the right track! What you have to subtract is the number of paths from (0,0) to (5,7) that pass through (4,3). To calculate this, all you have to do it multiply the number of paths from (0,0) to (4,3) by the number of paths from (4,3) to (5,7).

I think you can do the rest!

Tell me if you need any help!

:)

lokiisnotdead May 21, 2020

#4

#5**0 **

By the way, this problem is really similar to yours, I think this could help you a lot :)

lokiisnotdead
May 21, 2020