mean = .6 * 50 + .2 * 20 + .2 * 10 = 30 + 4 + 4 = 38 p
variance = (30-38)^2 + (4-38)^2 + (4-38)^2
A bag contains a large number of coins. 60% are 50p coins. 20% are 20p coins. 20% are 10p coins.
Find the mean and the variance of the values of this population of coins.
1 answer