There are more than four coins in my pocket. The total value of them is 25p. I pick a coin at random. The probability that will take out a 1p is 1/4.
How many, and which coins do I have in my pocket?
There are more than four coins in my pocket. The total value of them is 25p. I pick a coin at random. The probability that will take out a 1p is 1/4.
How many, and which coins do I have in my pocket?
The number of coins must be a multiple of 4, otherwise the probability of taking out a 1p coin could not be exactly 1/4.
So, with 8 coins, a solution is: 10, 5, 2, 2, 2, 2, 1, 1
There may be other solutions. I haven't tried any others.