GMAT Math Practice Test #1

Answer: B -The size of each section is to be selected in such a way, it divides both 576 and 488 exactly. So you have to find HCF of 576 boys and 448 girls. It is 64

576 = 2 x 2 x2 x 2x2x 2x 3x 3
448 = 2 x 2 x2 x 2x2x 2x 7
Highest Common Factors = 2 x 2 x2 x 2x2x 2 = 64

Key takeaway: The Highest Common Factor (HCF) is the largest positive integer that divides all the given numbers. Hence the HCF is the biggest size for forming groups.