Question

A single frame of $35$ mm film is about three-quarters of an inch long. A film reel holds up to $1000$ feet of film. Find the number of reels required for a $2:47:00$ ($2$ hr $47$ min) film shot at $24$ frames per second.

• A. 13
• B. 14
• C. 15
• D. 16

Answer 1

The correct option is D 16

There are $12$ inches in one foot, so a reel is $12\times 1,000=12,000$ inches long. Set up a proportion to determine how many frames per reel: $=$ $\frac{1frame}{\frac{3}{4}}=12000$

$\frac{3}{4}x=12000$

Cross-multiply to get $\frac{3}{4}x=12000$.

Divide both sides by $\frac{3}{4}$ to get $x=16,000$ frames per reel. Next, find the number of frames the film requires.

Convert the time to seconds.

There are $60$ minutes in an hour, so $2$ hours and $47$ minutes is equal to $(2\times 60)+47=167$ minutes.

There are $60$ seconds in a minute, so there are $60\times 167=10020$ seconds in this film.

If each second consists of $24$ frames, then there are $24\times 10020=240480$ frames in this film.

To determine the number of reels, divide by the number of frames per reel: $=15.03$ reels. Because $15$ reels does not hold quite enough frames, the film requires $16$ reels, which is (D).