Question

In a game, a participant pays Rs. 20 to roll a
dice. If he gets a prime number, he wins Rs.
30; if he gets a composite number, he loses his
money; and if he gets neither prime nor
composite, he gets Rs. 50. What is his average
profit percentage?

Answer 1

I'm guessing this is a standard 6-sided die with sides 1-6? (let me know if this is incorrect).

if so: 4 and 6 are composite, 2, 3, and 5 are prime, and 1 neither prime nor composite.

for each outcome, multiply (probability of that outcome)*(profit for that outcome).

for the composite numbers, for example, the probability of getting either 4 or 6 is 2/6 or 1/3, and the associated profit is (-20) since he loses all his money. so (1/3)(-20) so far.

repeat this logic for the other two outcomes. then take the final result as a percentage out of 20.