Hi LUANDATO,
We're told that Tom found a box of 220 baseball cards, he wanted to save AT LEAST 50 percent of the cards for himself and split the remaining cards evenly among his 4 younger brothers so that they would each have the SAME number of cards. We're asked for the LOWEST possible number of cards that Tom can save for himself under these conditions. This question can be solved with some Number Properties and TESTing THE ANSWERS.
Since Tom has 4 brothers, the total number of cards that he gives to them MUST be a multiple of 4. Thus, we're looking for the LEAST answer that is AT LEAST half of 220 and leaves us with a remaining number of cards that is a multiple of 4. We can use the 'rule of 4' to quickly determine which number that is.
The 'rule of 4': a number is divisible by 4 if the last 2 digits from a number that is divisible by 4.
For example....
132 is divisible by 4 because '32' is divisible by 4
10,525 is NOT divisible by 4 because '25' is NOT divisible by 4.
We're asked for the LEAST number of cards that Tom can keep for himself, so let's start with Answer A:
Answer A = 110 cards
If Tom keeps 110 cards for himself, that leaves 220 - 110 = 110 cards for his 4 brothers.
However, 110 is NOT divisible by 4 (because '10' is NOT divisible by 4), so this CANNOT be the answer.
Answer B = 112 cards
If Tom keeps 112 cards for himself, that leaves 220 - 112 = 108 cards for his 4 brothers.
However, 108 IS divisible by 4 (because '08' IS divisible by 4), so this MUST be the answer.
Final Answer: B
GMAT assassins aren't born, they're made,
Rich
