Question

A bag consists of 4 different colored marbles.
The probability of drawing each is as follows:
P (Blue)=. 4 P (Red)= .2 P (Purple)= .3 P (Black)= .1

You draw a marble out of the bag and then replace it.

What is the probability that you draw:

a. A red marble first and a blue marble second?

b. A black marble first and a purple marble second?

c. A red or blue marble?

d. A gray marble?

Answer 1

as long as you REPLACE
.2 * .4
.1 * .3
.2 + .4 http://www-math.bgsu.edu/~albert/m115/probability/add_probs.html
0 because no gray in the bag

Answer 2

note
probability of blue or red or purple or black better be 1.000000 :)
add them up to check