Melilla, Tasha, and Chester plan to fly on a jetliner that

[BTGmoderatorLU]

Source: Magoosh

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 websites allow 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?

A. 3/35
B. 1/5
C. 4/21
D. 6/35
E. 1/7

The OA is C

[Scott@TargetTestPrep]

Source: Magoosh

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 websites allow 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?

A. 3/35
B. 1/5
C. 4/21
D. 6/35
E. 1/7

The OA is C

Let's say the seat numbers are:

AB CDE FG

We see that there are 7C2 = (7 x 6)/2 = 21 ways Chester and Melilla can choose 2 of the 7 seats to sit. However, in order for them to sit next to each another without an aisle between them, they must choose seats AB, CD, DE, or FG. Therefore, the probability they sit next to another is 4/21. (Note: Tasha is a non-factor here since she can sit at any seat that is not chosen by Chester or Melilla.)

Answer: C