If np > 5 and nq> 5 estimate p (fewer than 4) with n=13 p=0.4 by using normal distribution as an approximate to the binomial distribution if np < 5 or nq< then state that the normal approximation is not suitable.

The Normal approximation to the binomial 

is as follows

mean=13(.5)=6.5 
variance=6.5(.5)=3.25 
Pr[fewer than 4]= 
Pr[N<=3] Apply the continuity correction 
Pr[N<=3.5]~=Pr[Z<3.5-6.5/sqrt(3.25)]= 

Pr[Z<-1.66]=0.048457226

I hope my answer has come to your help. God bless and have a nice day ahead!