Look at the statement below.

“All dogs are mammals.”

Which of these is a logically equivalent statement?
Answer
All dogs are furry.
If it is not a dog, it is not a mammal.
If it is not a mammal, it is not a dog.
All animals that are not dogs are not mammals.

Question

Look at the statement below.
 
“All dogs are mammals.”
 
Which of these is a logically equivalent statement?
Answer    
   All dogs are furry. 
   If it is not a dog, it is not a mammal. 
   If it is not a mammal, it is not a dog. 
   All animals that are not dogs are not mammals.

anonymous · Answer

third one is the "contrapositive" and it is logically equivalent

anonymous · Answer

first statement can be made into an "if then" statement by rewriting as "if it is a dog, then it is a mammal"
contrapositive is 
If it is not a mammal, then it is not a dog

anonymous · Answer

Gotcha thanks!