If C = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10} and D = {numbers divisible by 3 from 1 to 21}, what is C ∩ D?
A. {1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 15, 18, 21}
B. {3, 6, 9, 12, 15, 18, 21}
C. {3, 6, 9}
D. { }

Question

If C = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10} and D = {numbers divisible by 3 from 1 to 21}, what is C ∩ D? 
A. {1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 15, 18, 21} 
B. {3, 6, 9, 12, 15, 18, 21} 
C.  {3, 6, 9} 
D. { }

hartnn · Answer

list the numbers divisible by 3   from 1 to 21

poohbear · Answer

Well, there aren't much numbers that are divisible by 3 from 1 to 21. So, just look at the answers and see if some of the number from C and D are matching.

poohbear · Answer

C ∩ D, intersecting numbers of C and D

anonymous · Answer

so B?

poohbear · Answer

Well, it can't be B because 12, 15, 18, and 21 aren't in set C.