1. a. Repetition is not allowed, therefore the probability is (9/10)( 8/9)(7/8)(6/7) = 0.60

   b. only odd digits:  (5/10)(4/9)(3/8)(2/7) = 0.0238

2. a. Outcomes:  (heads, heads); (heads, tails); (tails, heads); (tails, tails)

   b. Find the probability of the following events.
	- the coin does not come up heads on either flip

(1/4) = 0.25

	- the coin comes up heads on both flips.

(1/4) = 0.25

	- the coin comes up heads exactly once.

(2/4) = 0.50

	- the coin comes up heads three times.
 0 (possibility not in sample space)

3. a. What is the probability that the teacher will use either red or orange ink?

        0.4 + 0.1 = 0.5

   b. What is the probability that the teacher will use purple ink?

1 - (0.4 + 0.3 + 0.1) = 0.2

4. a. Find the mean of this model.

  b. Find the standard deviation of  the model.

   c. How much money would you expect to win or lose if you play this game once a week for the next year?

(-1.75)(52 weeks) = -91

lose about $91