The percentage of winning if 20 winning numbers are randomly selected from numbers 1 to 80 is 12.48%.
Given There are 80 numbers from which 20 numbers are selected randomly in a game of Keno by player and after selection of 20 winning numbers again 20 numbers are selected and player wins if the player has correctly selected 3,4,or 5 of the 20 winning numbers.
Probability is the chance of happening an event among all the events possible.
Probability of winning is calculated as under:
Probability=
We have taken C(20,3) because player will win if 5 numbers are selected from 20 winning numbers.
We have taken C(60,17) because after selection of 20 numbers 60 numbers will left from 80 and after winning from 3 numbers 17 numbers left and from total 80, 20 numbers are taken.
=C(20,3)C(60,17)/C(80,20)
=(20!/3!17! * 60!/17!43!)/80!/20!60!
=1140*387221678682300/35353161422121743200
=12.48%
Hence the probability of winning is 12.48%.
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