Name____________________________________________
Topics in Pre-Calc II – Probability with Tree Diagrams CLASSWORK
Date _____
LEARNING GOAL #1: Dependent Probability (PART II)
Model Problem: A box contains 4 red and 2 yellow tickets. Two tickets are randomly selected from the box
one by one without replacement. Find the probability that:
a) both are red
b) both are the same color
c) first is red and second is yellow
e) at least 1 red
f) at most 1 yellow
d) one red and one yellow
LEARNING GOAL #2: Tree Diagram Probability
Model Problem #1: Carl is not having much luck lately. His car will only start 80% of the time and his
motorbike will only start 60% of the time. The tree diagram below illustrates his current situation.
Use the tree diagram to determine the probability that
(a) both will start
(b) car starts but the motorbike does not
(c) one of the modes of transportation does not stat
Model Problem #2: A bag contains 5 red and 3 blue marbles. Two marbles are drawn simultaneously from
the bag, without replacement. The tree diagram that illustrates this situation is given below:
Use the tree diagram to determine the probability that
(a) both not be red
(b) at least one will be red
(c) both not the same color
CREATING AND LABELING TREE DIAGRAMS WITH PROBABILITY

THINGS TO REMEMBER:
1. P(A’) = 1 – P(A)
2. With DEPENDENT events, you must worry about adjusting your totals
2. There is a biscuit tin on a shelf. The tin contains one chocolate biscuit and nine plain biscuits.
A child chooses a biscuit from the tin. The child eats the biscuit and chooses another one from the tin.
a) Create and label a probability tree diagram that represents the possible outcomes for this event.
b) Using this tree diagram find the probability that
(i)
both biscuits are chocolate
(ii)
at least one of the biscuits is chocolate
3. A container holds 3 red, 7 white, and 2 yellow balls. A ball is chosen at random from the container and is
not replaced. A second ball is then chosen.
(a)
Draw and label a probability tree diagram to illustrate this information.
(b)
Find the probability that
(i)
the picks are not the same color
(ii)
the first pick is white and the second is black
(ii)
the picks are different colors