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A graphics card has on board memory of $1$ MB. Which of the following modes can the card not support?

1. $1600 \times 400$ resolution with $256$ colors on a $17$ inch monitor
2. $1600 \times 400$ resolution with $16$ million colors on a $14$ inch monitor
3. $800 \times 400$ resolution with $16$ million colors on a $17$ inch monitor
4. $800 \times 800$ resolution with $256$ colors on a $14$ inch monitor

Just measure the memory required for the given resolution. The screen size has nothing to do with the memory required and is given just for the sake of it. Each pixel is represented using a color. So, we need to find the number of pixels and multiply by the amount of storage required for color.

A. 256 colors means 8 bits for color representation meaning 1 byte. So, 1600 * 400 resolution requires 640 kB. We have 1 MB, so fine.

B. 16 million colors require 24 bits or 3 bytes. So, 1600 * 400 resolution requires 640 k * 3 = 1920 kB which is over our on board memory. So, not possible.

C. Again 3 bytes for a color. 800 * 400 resolution requires 320 k * 3 = 960 kB which is fine as we have 1 MB on board.

D. 256 colors require 1 byte. 800 * 800 resolution requires 640 k * 1 = 640 kB which is again fine.

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1600 * 400 resolution requires 640 kB. how [email protected] pls help

1600*400=640000 B=640k and because since there are 256 colors we need 8bit or 1Byte to represent all colors. So 1600*400 resolution requires 640kB.

Hope this helps.
B=640k ...?

What is B?
@Arjun Sir

Why 1KB is not equal to 1024 Bytes here... Please tell the cases where 1K= 1000 units and where 1K = 1024
Will the number of bits required for color representation always be a multiple of 8?