Answer
$1.802783973\times10^{-7}$
I would consider this event unlikely to occur because the probability is too small.
Work Step by Step
$p=1/5=0.2, n=20$
$P(X\geq15)=\sum P=_{20}C_{15}0.2^{15}0.8^5+_{20}C_{16}0.2^{16}0.8^4+_{20}C_{17}0.2^{17}0.8^3+_{20}C_{18}0.2^{18}0.8^2+_{20}C_{19}0.2^{19}0.8^1+_{20}C_{20}0.2^{20}0.8^0=1.802783973\times10^{-7}$
I would consider this event unlikely to occur because the probability is too small.
