.Which of the following is not a well-defined set?
a. hospitals in Iligan City
b. letters in the word virus
c. group of front liners
d. vowels in the word pneumonia

______2. What is the cardinality of Set A described as all odd numbers less than 13?
a. 6 b. 5 c. 4 d. 3

______3. If set R = { W, O, N, D, E, R }, how many subsets does R have?
A. 6 B. 8 C. 32 D. 64

For numbers 4-8, refer to the given set, Given:
A = {2,4,6,8,10,12},
B= {3,6,9, 12. 15, 18},
C = {0,6,12,18}

______4. What is A-B?
a.{2,4,6,8,9} b. {2,4,6,8}
c. {3,6,9,12,15,18} d.{2,4,8,10}
______5. What A-C?
a. {2,4,6,8,9} b. {2,4,8,10}
c. {3,6,9,12,15,18} d.{2,4,8,10}
______6. What is B-C?
a. {3,9,15} b. {3,6,15,18}
c. {3,6,9,,15,18} d.{3,4,6,8,10}
______7. What is A U B?
a. {2,4,6,8,10} b. {2,3,4,6,8,9,10,12,15,18}
c. {2,4,5,6,9} d. {0,2,4,6,8,9}
______8. What is A ∩ B?
a. {b,d} b. {4,12}
c.{6,12} d. {3,4}