Question

Let set = A the set of all positive integers less than twenty five that are divisible by 5.what is the cardinality of this set

Answer 1

Answer:

4

Step-by-step explanation:

A= {5,10,15,20}

25 is not included because it is said that set A contains multiples of 5 that are less than 25.

Also 0 is not included because 0 is neither positive nor negative.

Answer 2

EXPLANATION

Set of integers: n:n∈Z

Set of integers divisible by 5: 5n:n∈Z

Positive integers: 5n>0⟹n>0

Less then 25 5n<25⟹n<5

Putting all of it together:

5n:n∈Z; 0<n<5

And n can be 1,2,3,4so the set contains {5,10,15,20}