Question

Am I correct?
What is the contrapositive of the following statement?

“If it does not have four legs, then it is a fish.”

If it is a fish, then it does not have four legs.

If it has four legs, then it is not a fish.

If it is not a fish, then it has four legs.

If it does not have four legs, then it is not a fish.


* i know:
statement: if p then q
contrapositive: if not q then not p

but this is sort of confusing im just making sure i understand this correctly*

Answer 1

i believe the answer is: If it is not a fish, then it has four legs.

Answer 2

@satellite73 can you help?

Answer 3

In general, the contrapositive of a logical statement:
if P then Q
is
if not Q then not P.

In your example, P is "it does not have four legs" and Q is "it is a fish".

Hence, your answer is exactly right.

Answer 4

contrapositive of
if P then Q is
if not Q then not P

Answer 5

...as not Q is "it is not a fish" and not P is "it does have four legs"

Answer 6

what jamesj said

Answer 7

thanks :)

Answer 8

“If it does not have four legs, then it is a fish.”
if P then Q
P: it does not have four legs
Q: it is a fish
not Q: it is not a fish
not P: it had four legs

if it is not a fish, then it has four legs