GMAT Question of the Day #116 - Reducing Unnecessary Calculation

This blog post relates to question #116 from the Official Guide for GMAT Review, 2017.

What intimidates most students here, and sends them spiraling into a black hole of unnecessary calculation, is the first line of the table: 10.8% of 37. It’s not as bad as it looks, but we’ll come back to that…

Do you see a friend? Isn’t 66.7% = 2/3. Since we can’t have fractional marbles, the total number of marbles in Bag Q must be a multiple of 3… in other words,

So, we can dispose of A, D, and E. Let’s try C – the number of marbles in Bag Q is 12

Total Marbles = 37 + 12 + 32 = 81

Back to 10.8% of 37.

• What’s 10% of 37?
• What’s an integer that’s a little more than 10% of 37?
• 4

See, that wasn’t so bad.

Takeaways:

1. Be on the lookout for your friends, and numbers close to your friends.
2. Use context to eliminate answers – you can’t have fractional marbles, people, cats, dogs, etc.
3. Don’t be intimidated by numbers that aren’t your friends… the people at GMAC are just trying to mess with your head. Don’t let them.

 John is a Senior MyGuru GMAT tutor based in Chicago, but is also the founder of Owl Test Prep . We encourage you to check out their web-site and YouTube channel.