Probability of 3 coins landing on diagonals

[alan4cult]

Hello, I have a problem with this question
http://www.icefusionf1.com/prob.png
My thoughts:
I think it is better to work out the probability of the 3 coins being placed on the diagonals.

Please help?

 

[tiny-tim]

… one coin at a time …

I think it is better to work out the probability of the 3 coins being placed on the diagonals.

No.

In problems like this, generally start "the first one …, then the second one …, then …"

In this case, place the thre coins one at a time.

The first coin can go anywhere - no restriction.

With the first coin fixed, how many options are there for the second coin?

Then, with both the first and second coins fixed, how many options are there for the third coin?