Logic Quiz 1

Which examples would support the conjecture that the sum of an even integer and an odd integer will be odd? Check all that apply.

• 2 + 5 = 7

• -3 + 4 = 1

• 6 + -9 = -3

• There are only counterexamples.

Tags

CCSS.6.NS.C.7C

For a conjecture to be true, it must be true...

• in most cases.

• in all cases.

• on Thursday mornings.

• at least once.

Tags

CCSS.RI.8.1

CCSS.RI.8.8

CCSS.RL.11-12.1

CCSS.RL.8.1

CCSS.RL.9-10.1

What is a counterexample?

• A generalism that cannot be applied to a specific case

• A specific case that help to prove a conjecture

• A general case that is supported by specific examples

• A specific case for which a conjecture is false

Tags

CCSS.L.8.6

CCSS.L.9-10.6

CCSS.W.11-12.2D

CCSS.W.8.2D

CCSS.W.9-10.2D

Which of the following is a counterexample to the conjecture that the product of two positive numbers is always greater than either number?

• 1 x 5 = 5; 5 is not greater than 5

• 2 x 3 = 6; 6 is greater than 2 and 3

• -3 x 4 = -12; -12 is not greater than -3 or 4

• -1 x -2 = 2; two is greater than -1 and -2

Tags

CCSS.7.NS.A.2A

CCSS.7.NS.A.2B

In order to prove a conjecture false, ...

• you need only one counterexample.

• you need several counterexamples.

• you need to show all cases are false.

According to the graph, which is a reasonable conjecture?

• More girls will participate in high school lacrosse in Year 8 than those who participated in Year 7.

• The number of girls participating in high school lacrosse will exceed the number of boys participating in high school lacrosse in Year 9.

• There were more girls participating in high school lacrosse in Year 5 than in Year 1.

• More girls will participate in lacrosse in the United States during Year 8 than in Sweden.

Tags

CCSS.HSF.IF.A.2

The 11th figure will be a...

• triangle

• square

• rhombus

• circle

Tags

CCSS.4.G.A.3

How many triangles will be in the next figure?

• 7

• 11

• 9

• 10

Tags

CCSS.HSF.BF.A.2

Which of the following provide a counterexample to the claim:

"If two angles are supplementary, then they are not congruent."

•  $40\degree\ and\ \ 140\degree$ 

•  $80\degree\ and\ \ 80\degree$ 

•  $30\degree\ and\ \ 150\degree$ 

•  $90\degree\ and\ \ 90\degree$ 

Tags

CCSS.7.G.B.5

Which is a counterexample to the following statement?

If an angle is obtuse, then it is $125\degree$ .

•  $90\degree$  

•  $57\degree$  

•  $160\degree$  

•  $180\degree$