Question
A die is tossed twice. Getting a number greater than 4 is considered a success. Find the variance of the probability distribution of the number of successes.
Solution
The number of successes is a random variable. Let us denote it by X. X can take the values 0, 1, 2.
The number greater than 4 is 5 or 6. Let S denote the successes in getting 5 or 6.
X takes the values 0, 1, 2 with probabilities 
respectively.
The number greater than 4 is 5 or 6. Let S denote the successes in getting 5 or 6.
X takes the values 0, 1, 2 with probabilities respectively.
