9709 P63 - Jun 2012 - Q4
2940
The six faces of a fair die are numbered 1, 1, 1, 2, 3, 3. The score for a throw of the die, denoted by the random variable W, is the number on the top face after the die has landed.
- Find the mean and standard deviation of W. [3]
- The die is thrown twice and the random variable X is the sum of the two scores. Draw up a probability distribution table for X. [4]
- The die is thrown n times. The random variable Y is the number of times that the score is 3. Given that E(Y) = 8, find Var(Y). [3]
