Answer:
The dice has 6 options:
if the outcome is 5, player wins 50
if the outcome is 6, player wins 200
if the outcome is another number, the player does not win anything.
Now, remember that the expected value can be written as:
E = ∑xₙpₙ
where xₙ is the event n, and pₙ is the probability of that event.
for a dice, the probabilty for each number is 1/6
The expected value is:
E = (1/6)*(0 + 0 + 0 + 0 + 50 + 200) = 41.66
The expected gain will be E - 100 (because the player pays 100 in order to play)
Then the expected gain is:
G = 41.66 - 100 = -58.33
The standard deviation can be written as:
s = √( ∑(x - x)^2/n)
where x is the mean, in this case the mean is:
(200 + 50 + 4*0)/6 = 41.66 and n = 6.
s = √( (1/6)*(4*(0 - 41.66)^2 + (50 - 41.66)^2 + (200 - 41.66)^2) ) = 73
So we have a lot of standard deviation on Y.
