A) 0.1211
B) 0.3889
C) 0.9782
Explanation:
A)  We use a binomial distribution for this:
[tex]_nC_r(p)^r(1-p)^{n-r}
\\
\\_{12}C_3(0.42)^3(1-0.42)^{12-3}=_{12}C_3(0.42)^3(0.58)^9=0.1211[/tex]
B)  Using a graphing calculator, we find the sum of the binomial probabilities from 0 up to (not including) 5:  0.6111.  Now subtract this from 1, since we want everything greater than or equal to 4:  1 - 0.6111 = 0.3889
C)  Using a graphing calculator, we find the sum of the binomial probabilities from 0 up to (not including) 8:  0.9782