State the converse and contrapositive of each of the following statements:
(i) p: A positive integer is prime only if it has no divisors other than 1 and itself.
(ii) q: I go to a beach whenever it is a sunny day.
(iii) r: If it is hot outside, then you feel thirsty.
We know that
the converse of a given statement “if p, then q” is if q, then p and the contra positive of the statement if p, then q is “if ∼q, then ∼p”.
(i) The statement p can be rewritten as
If a positive integer is prime, then it has n divisors other than 1 and the number itself.
Converse of statement p is
If a positive integer has no divisors other than 1 and the number itself, then it is prime.
Contra positive of statement p is
If a positive integer has divisors other than 1 and the number itself, then it is not prime.
(ii) The statement q can be rewritten as
If it is a sunny day, then I go to a beach.
Converse of statement q is
If I go to a beach, then it is a sunny day.
Contra positive of statement q is
If don’t go to a beach, it is not a sunny day.
(iii) Converse of statement r is
If you feel thirsty, then it is hot outside.
Contra positive of statement r is
If you don’t feel thirsty, then it is not hot outside.