Carcass wrote:
For how many positive integer x is 130/x an integer?
(A) 8
(B) 7
(C) 6
(D) 5
(E) 3
In order for 130/x to be an integer,
x must be a divisor of 130So, the question is really asking us to determine the number of positive divisors of 130.
To do this, we can use the following rule:
If the
prime factorization of N = (p^
a)(q^
b)(r^
c) . . . (where p, q, r, etc are different prime numbers), then N has a total of (
a+1)(
b+1)(
c+1)(etc) positive divisors.
Example: 14000 = (2^
4)(5^
3)(7^
1)
So, the number of positive divisors of 14000 = (
4+1)(
3+1)(
1+1) =(5)(4)(2) = 40
Now onto the question.......
130 = (2)(5)(13) = (2^
1)(5^
1)(13^
1)
So, the number of positive divisors of 130 = (
1+1)(
1+1)(
1+1) =(2)(2)(2) = 8
Answer: A