Question

Question 34
The number of common prime factors of 75, 60, 105 is

(A) 2
(B) 3
(C) 4
(D) 5

Answer 1

Prime factorisation of 75, 60 and 105


$75=3\times 5\times 560=3\times 5\times 2\times 2105=3\times 5\times 1\times 7$
Common factors of 75, 60 and 105 are 3 and 5.
Hence, the number of common prime factors of 75, 60 and 105 is 2.