Michelle asked:
In 4-spot Keno, you pick 4 numbers out of 80. If all 4 come up, you win $120. If 3 of your 4 come up, you win $4. If 2 come up, you win $1, with 1 or 0 numbers giving no prize.
Let X be the winnings from a game of 4-spot Keno. The probabilities of each outcome can be obtained from the hypergeometric distribution and are as follows:
x P(X = x)
$0 – 234407/316316
$1 – 67260/316316
$4 – 13680/316316
$20 – 969/316316
The amount you would expect to win from a game of 4-spot Keno is (3 decimal places)
One Comment on "If someone could solve this little maths problem that would be great?"
Well i was in the same boat as you, but i did some research so i could work it out myself. By the way you’ve put $20 instead of $120 in the probabilities.
To find the Expected Value, you need to follow this formula
E(x)= x1 p1 + x2 p2 + … + xn pn
= Σ xi pi (Or) Σ pi xi [i = 1, 2, 3, ... n]
= Σ px
If that looks confusing, then just concentrate on the first line.
x = $ value of winnings
p = probability of the event
E(x) = ((0*(234407/316316) + ((1*(67260/316316)) + ((4*(13680/316316)) + ((120*(969/316316))
= 0.753
Quiz 5 tells me that this answer is correct.
cya in STAT1201