# Math review for editors (10 questions)

Musicvid wrote on 6/28/2018, 3:18 PM

Basic Math Review for Editors – June, 2018

1. I have a screen 2000w x 2000h pixels. What is the area, in pixels? For 4000 x 4000 pixels?

2. What is 256^3?

3a. I have a rectangular video 1440w x 1080h pixels. What is the nearest simple ratio of width to height? If your answer is a decimal, convert to a fraction or ratio.

3b. By what factor would I multiply the original width of 1440 to get a display width of 1920 pixels? What is the new W:H ratio?

4. If I add 25% to the number 10,000, then subtract 25% of the total, what is the sum?

5. If I have a screen that is 3840w x 2160h, is it the same shape (not size) as a rectangle 720w x 480h?

6. I have a video stored at 720w x 480h. If I apply a factor of .9091 to the width, what are the new dimensions? For a factor of 1.2121?

7. I have an uncompressed video That is 200MB. If I compress it by a ratio of 25:1, what is the new size in MB?

8. I have a video that is 10 minutes long. It was encoded at 12 Megabits per Seond (Mbps).  What is the approximate video file size in Megabytes (MB), excluding audio and metadata. Use the formula:

Bitrate (Mbps) x Time (Sec) x .125 = File Size (MB).

9. If I have 256 bits of data [0,255], and the subrange [0,15] and [236,255] are excluded, what percentage of the original data remains (round to nearest digit).

10. Bonus: I have a light shining on a white screen (assuming 100% reflectance. In order for the camera to see twice as much light (f8 to f16, or ISO 1200 to 600, for example), how much more energy does the light source require (assuming traditional lighting with a normal log energy curve, not a gated pulse)?

I'll make this to multiple choice if no perfect scores.

john_dennis wrote on 6/30/2018, 8:31 AM

I sent you a messasge with a link to my answer sheet.

Musicvid wrote on 6/30/2018, 10:31 AM

I'll check it tomorrow but I suspect you nailed it. You've simply known me too long.

Musicvid wrote on 6/30/2018, 6:28 PM

J_D nailed the test, but missed the bonus with a really good guess.