Number of combinations possible = 4! / 2! 2! = 6
Each of these has probability 1/2*1/2*1/2*1/2 = 1/16
Required probability = 6 * 1/16 = 3/8
Is this multiple choice, or.... ?
The logarithm and the exponential are inverse function:

So, we have

And so in particular we have

We just need to perform the indicated division:
3/4 = 0.75
that is the solution as decimal, they are equivalent