value of xy? (GMAT Prep 2)

[alex.gellatly]

If x and y are positive integers, what is the value of xy?

1. The greatest common factor of x and y is 10.
2. The least common multiple of x and y is 180

[Anurag@Gurome]

If x and y are positive integers, what is the value of xy?

1. The greatest common factor of x and y is 10.
2. The least common multiple of x and y is 180

Product of two positive integers = (LCM of the integers)*(GCF of the integers)
Hence, we need both the statements to answer the question.

The correct answer is C.

[Anurag@Gurome]

Picking Numbers:
Statement 1: Consider the following two cases,

• x = 10 and y = 20 ---> xy = 200
  x = 10 and y = 30 ---> xy = 300

Not sufficient

Statement 2: Consider the following two cases,

• x = 4 and y = 45 ---> xy = 180
  x = 90 and y = 180 ---> xy = 90*1800

Not sufficient

1 & 2 Together: xy = 10*180 = 1800
Sufficient

The correct answer is C.