There’s nothing like a mathematical Brain Twister to put you in the holiday spirit … right? ðŸ™‚ Let’s get started…

Melilla, Tasha, and Chester plan to fly on a jetliner that has seven seats per row. The middle row consists of three seats, which are separated on each side by an aisle and two seats. The website allows users to choose specific seats, but a computer glitch only assigns rows, not the specific seat within that row. Assuming Melilla plans to book three tickets in the same row, what is the probability that Chester will sit next to Melilla, without any aisle between them?

- 3/35
- 1/5
- 4/21
- 6/35
- 1/7

*Want to check your work? We will publish the answer and explanation this Friday…we’re mixing things up a bit this week so we don’t distract everyone celebrating Christmas. Happy Holidays! ðŸ™‚*

Does order matter here? I considered there are 4 possible cases where this could work.

The total number of possibilities is 7C2 since I am trying to select 2 out of 7 seats. That makes the probability = 4 / 21. Option C. Is my logic correct?

Great job! Yes! You can see the full answer and explanation here: http://magoosh.com/gre/2014/magoosh-brain-twister-probability-with-a-high-chance-of-turbulence-explanation/

4/21

Yes, it’s C. Their are four positions for two people to sit next to each other. Make it eight as they can interchange the sits. All possible positions are two out of seven when order matters, it is 42. The probability is 8 out of 42 or 4/21. C

Nice explanation ðŸ™‚

Yep, that’s it!