Grade 8, Unit 7
PART 1: Appropriate Graphs & Misrepresenting Data
Name :____________________
Types of Graphs:
Type of Graph
Strengths

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Circle Graph


Bar Graph


Pictograph



Limitations
Compares parts to a whole
Each response is shown as
a percent
Sizes of sectors compare
results



Graph does not show totals
Totals cannot be calculated
Difficult to draw (by hand)
Height of bars compare
responses
Scale can be used to find
totals
Easy to draw

May be difficult to read
depending on where the
bars end
Does not show percent
Lengths of rows gives
immediate comparison
Visually Appealing
Key can be used to find
totals




Quantity of symbols
Part symbols difficult to
read and draw
Does not show percent



Line Graph

Double Bar Graph

Shows change over time
Easy to draw
Can estimate values of
continuous data
Can be used to find totals


Does not show percent
May be difficult to read
depending on scale.
Used to compare two sets
of data

May be difficult to read
depending on scale.
To complete on loose leaf: p.387-388 # 3, 4, 5, 6
Misrepresenting Data
Different formats of Graphs may lead to misinterpretations of data. Discuss what may
be misinterpreted in each of the following examples:
Graphs
Misinterpretations
To complete on loose leaf: p.399-400 # 3, 4, 5, 6, 7
PART 2: Statistics & Probability
Name :____________________
Section 7.3: Probability of Independent Events
Independent Events - Two events are independent when one event does not affect the
other.
Examples:
Tossing a Coin – The outcome if the 1st toss does not affect the
outcome of the 2nd toss.
Rolling a Die – If you roll a six on the first roll, the likelihood of
rolling a six on the 2nd roll is not affected by the 1st roll.
Tree Diagram
Example 1:
The pointer is spun twice. Landing on green and landing on blue are
independent events. Draw a tree diagram to determine the probability of
landing on red twice.
Tree Diagram
Probability of red on the first spin: P (Red) =
Probability of red on the second spin: P (Red) =
Probability of landing on red twice = P (red) on 1st spin X P (red) on 2nd spin
P (red and red) =
Question: What is the probability of spinning a blue then a red?
Answer: Look at the tree diagram.
P (Blue) =
P (Blue and Red) =
P (Red) =
Example 2: A coin is tossed and a die is rolled. Find the probability of:
(A) Tossing heads and rolling a six.
(B) Tossing heads or tails and rolling an even number.
Example 3:
A bag of marbles contains 5 red, 7 blue and 8 yellow. Claire removes one
marble, records its color and returns it to the bag and picks a second
time. Find the probability of:
(A) Picking a yellow marble both times.
(B) Picking a marble that is NOT yellow and the 2nd marble is blue.
p.411-413 #3-8,10,12
To complete on loose leaf: p.411 - 413# 3-8, 10, 12
Section 7.4: Solving Problems Involving Independent Events
Recall: P (A and B) = P (A) X P (B)
Example 1:
Tristan is tossing a coin, Anthony is spinning a pointer and Matthew is
rolling a die.
Coin: heads or tails
Spinner: Red, green or blue
Die: 1-6
(A) Use a tree diagram to find the following probabilities.
Diagram
i. Tossing heads, rolling a three and landing on red.
ii. Tossing tails, rolling a 4 or 6 and landing on blue.
(B)
What is P (Heads)?
What is the P (rolling a 3)?
What is P (Red)?
(C)
What is the probability of tossing heads, rolling an even number and
spinning a green?
Example 2:
The Weather Network is predicting a 40% probability of rain in Gander, a
75% chance of rain in Mount Pearl and a 15% chance of rain in Ferryland.
What is the probability that it will rain in all three places?
Written as a:
Percent
Decimal
Fraction
P (rain in Gander) =
P (rain in Mount Pearl) =
P (rain in Ferryland) =
P (rain in Gander, Mt. Pearl and Ferryland) =
To complete on loose leaf: p.420-422 # 4 - 6, 9 – 11, 13, 14