Answer
a)0.328
b)0.41
c)0.738
d)It is not an unusually low probability.
Work Step by Step
a) $P(X=0)={5\choose 0} \cdot (0.2)^0\cdot (0.8)^5=0.328.$
b)$P(X=1)={5\choose 1} \cdot (0.2)^1\cdot (0.8)^4=0.41.$
c)$P(X=0 \ or X=1)=P(X=0)+P(X=1)={5\choose 0} \cdot (0.2)^0\cdot (0.8)^5+{5\choose 1} \cdot (0.2)^1\cdot (0.8)^4=0.328+0.41=0.738$
d) No, it is not an unusually low probability, because 0.738 is really high, more than 0.05.