Answer
a)0.1201
b)The 50% success ratio is correct.
Work Step by Step
a) $P(X=8)={20\choose 8} \cdot (0.5)^{8}\cdot (0.5)^{12}=0.1201.$
b) The 0.252 probability stands for getting 8 or less overturns with a 50% success ration, so the 50% success ratio is correct.
