Answer:
P( top two horses are predicted incorrectly in incorrect order)
= 
Step-by-step explanation:
In the horse race the outcome can be predicted in 5! = 120 ways.
Now suppose the top two horses were predicted incorrectly in incorrect order. Now, the top horse can be predicted incorrectly in 4 ways.
Suppose the top horse was predicted to be in k-th position where k = 2, 3 ,4,5
so the second horse can be predicted to be in place from 1 to (k - 1)
So, the top two horses can be predicted incorrectly in incorrect order
in
= 10 ways
and for each prediction of the two the remaining horses may be predicted in 3! = 6 ways.
Hence ,
P( top two horses are predicted incorrectly in incorrect order)
= 
=
AB = BC
3x-4=5x-10
-4=2x-10
6=2x
3=x
AB = 3x-4
AB = 3 (3)-4
AB = 9-4
AB =5
Therefore, AB is 5.
BC = 5x-10
BC = 5(3)-10
BC = 15-10
BC= 5
11/8 or 13/8 is the answer.