Answer: about 66% probability
Explanation:
p = 0.8 is the success of a show up
q= 0.2 is the fail rate probability
Pr(at least 5 successful showups)
= (6 choose 5 )* 0.8^5 * 0.2 + (6 choose 6)* 0.8^6
= 6 * 0.8^5 *0.2 + 0.8^6
= 6* 0.32768*0.2 + 0.262144
= 0.393216 + 0.262144
= 0.65536 = 0.66
From MysticAlanCheng