Any help would be much appreciated!!

Let X be a random variable with P(x=-1)=P(x=0)= 1/4 and P(x=1)= 1/2.

Let S be the sum of 25 independent random variables, each with the same distribution as X. Calculate approximately

a) P(S<0)

b) P(S=0)

c)P(S>0)

Thank you!!