Problem Solving

Hi All,

We're told that a certain reel of film runs at 5/6 of a frame per second. We're asked how long it will take to run 2580 frames of the film. While this question involves some 'ugly' numbers, the answer choices are sufficiently 'spread out' that you can use estimation to get the correct answer (while avoiding a lot of step-heavy math).

If we 'round' the film speed to 1 frame/second and 'round down' the total number of frames to 2400 frames, then we would need 2400/1 = 2400 seconds to run the film. 2400 seconds = 2400/60 = 40 minutes, so we're looking for an answer that's relatively close to that... and only one answer comes close...

Final Answer: B

GMAT assassins aren't born, they're made,
Rich

BTGmoderatorDC wrote:If a certain reel of film runs at 5/6 of a frame per second, how long will it take to run 2580 frames of the film?

(A) 8.6 minutes
(B) 51.6 minutes
(C) 5.16 hours
(D) 5.8 hours
(E) 5.96 hours

OA B

Source: Veritas Prep

It will take 2580/(5/6) = 15,480/5 = 3096 seconds or 3096/60 = 51.6 minutes.

Alternate Solution:

We can set up a proportion: "5/6 of a frame is to 1 second as 2580 frames is to x seconds:"

(5/6)/1 = 2580/x

5/6 = 2580/x

5x = 6(2580)

x = 6(516) seconds

To convert to minutes, we divide by 60 (or 6 x 10), obtaining:

6 x 516 / (6 x 10) = 51.6 minutes

Answer: B