Counterexamples & Logic

If an animal is furry, then it is a hamster. What would be an appropriate counterexample?

• goldfish
• frog
• elephant
• cat

Tags

CCSS.HSS.CP.A.5

If it is a fraction, then it is a number between zero and one. What is an appropriate counterexample?

• 2/3
• 4/5
• 1/2
• 3/2

Tags

CCSS.6.NS.C.7A

CCSS.6.NS.C.7B

True or False: a counterexample is an example that makes a definition or conjecture incorrect

• True
• False

Identify the hypothesis and conclusion of the conditional statement:
If you give me twenty dollars, then I will be your best friend.

• Hypothesis: I will be your best friend
  Conclusion: you give me twenty dollars
• Hypothesis: you give me twenty dollars
  Conclusion: I will be your best friend
• Hypothesis: if you have to pay for friends
  Conclusion: then you probably should reevaluate your life
• Hypothesis: you will not have to pay twenty dollars
  Conclusion: if you have lots of friends

Tags

CCSS.L.2.1F

CCSS.L.8.1C

CCSS.L.8.3A

What is the hypothesis of the given Conditional Statement?

• Jimmy will go to Orlando
• Jimmy goes on vacation
• Jimmy will go to Orlando
• Who is Jimmy?

Tags

CCSS.HSS.CP.A.1

CCSS.HSS.CP.A.3

CCSS.HSS.CP.B.6

What is the conclusion to the statement?

• You like fried chicken
• You only like fried chicken from KFC
• You like KFC
• You hate KFC

Tags

CCSS.L.2.1F

CCSS.L.8.1C

CCSS.L.1.1J

CCSS.L.K.1D

What is the converse to this statement?

• If it isn't dark outside, then it is not night.
• If it is night, then it is dark outside
• If it is not night, then it is not dark outside.
• It is night.

When taking the converse we ___________ the hypothesis and conculsion

• negate
• switch
• highlight
• switch and negate

Which is a counterexample to the following statement?

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

•  $90\degree$  

•  $57\degree$  

•  $160\degree$  

•  $180\degree$  

Tags

CCSS.HSG.CO.A.1

Which is a counterexample to the following statement?

If  $LM\cong MN$  , then  $M$   is the midpoint of  $LN$  .

• 
• 
• 
• None of these

Tags

CCSS.HSG.CO.B.6

CCSS.HSG.CO.C.10