Question

for each given set, determine if the set is finite or infinite. if finite, give the cardinality.
set\tis the set finite or infinite?
(a) the set of integers greater than 7 and less than 13\t○ finite
cardinality:
○ infinite
(b) {20, 40, 60, 80, …}\t○ finite
cardinality:
○ infinite
(c) {p, s, u, v, y, z}\t○ finite
cardinality:
○ infinite

Explanation:

Step1: List integers 7<x<13

Integers: $8,9,10,11,12$

Step2: Count elements for (a)

Count: $n=5$

Step3: Analyze set (b)

Set has ellipsis: infinite elements

Step4: Count elements for (c)

Elements: $p,s,u,v,y,z$, count: $n=6$

Answer:

(a) finite, cardinality: 5
(b) infinite
(c) finite, cardinality: 6