Answer to Question #263769 in Discrete Mathematics for John

Question

Determine the cardinality of each of the sets, A, B, and C defined below, and prove the cardinality of any set that you claim is countably infinite.

A is the set of negative odd integers

B is the set of positive integers less than 1000

C is the set of positive rational numbers with numerator equal to 1

Answer 1

A.

$P=\infin$ , since the number of negative odd integers is infinite.

B.

$P=999$

C.

$P=\infin$ , since there are infinitely many positive rational numbers with numerator equal to 1.