Question

If the set A is defined as A = {x : x is a factor of 42 and is a prime number}. Then the number of elements in set A is ____ .

• A. 3

Answer 1

The correct option is A 3
Factors of 42 are 1, 2, 3, 6, 7, 14, 21, 42.
Out of these factors, 2, 3, and 7 are prime numbers.
A = {2, 3, 7}
$\therefore$ The number of elements in set A is 3.