Let the total number of coins be n. Then the number of 5c coins is 4n/8, etc.
I have $5 in mixed coins in a bag. The coins are either 5c, 10c or 50c and I have calculated the following probabilities.
P(5c) = 4/8
P(10c) = 3/8
P(50c) = 1/8
Any thoughts on how to go about finding how many of each coin there are?