Because 2,3,1,7>0 so 2 isn't the second number

We can put off:4 x 4=16(number)

But 2 isn't the second number so we can put off:16-4=12(number)

Because 2+1=3\(⋮3\) ; 2+7=9\(⋮3\) so 21 and 27 isn't a prime number

So we can put off:12-2=10(number) but 33 and 77 isn't a prime number

Answer:10-2=8(number)

There are: \(4\cdot3=12\left(ways\right)\) to form a two-digit number.

The prime numbers can be make are: 23;27;31;37;13;17;73 so there are 7 prime numbers can be make.

So the probability is: \(7:12=\dfrac{7}{12}\)