Answer : The value of
for the final reaction is, 
Explanation :
The following equilibrium reactions are :
(1)

(2)

(3)

The final equilibrium reaction is :

Now we have to calculate the value of
for the final reaction.
First half the equation 1, 2 and 3 that means we are taking square root of equilibrium constant and then add all the equation 1, 2 and 3 that means we are multiplying all the equilibrium constant, we get the final equilibrium reaction and the expression of final equilibrium constant is:

Now put all the given values in this expression, we get :


Therefore, the value of
for the final reaction is, 