Image file sizes

This is the calculation:

$$30\times10\times4=1200$$

$$50\times10\times4=2000$$

So the image needs 2000 bits.

$$2000\div8=250$$

So the image needs 250 bytes.

$$160\times95\times16=243200$$

So the image needs 243200 bits.

$$243200\div8=30400$$

So the image needs 30400 bytes.

$$2500\times1800\times12=54000000$$

So the image needs 54000000 bits.

$$54000000\div8=6750000$$

So the image needs 6750000 bytes.

The file size should be a number between 1 and 999, so 275 KB is the best option.

The file size should be a number between 1 and 999, so 3.8 MB is the best option.

$$240\times250\times4=240000$$

So the image needs 240000 bits.

$$240000\div8=30000$$

So the image needs 30000 bytes.

30000 B = 30 KB (= 0.03 MB)

$$3600\times2700\times16=155520000$$

So the image needs 155520000 bits.

$$155520000\div8=19440000$$

So the image needs 19440000 bytes.

19440000 B = 19440 KB = 19.44 MB (=0.01944 GB)

Let c be the colour depth.

$$600\times600\times c=360000c$$

So the image needs 360000c bits.

$$360000c\div8=45000c$$

The image needs 45000c bytes.

720 KB = 720000 B, so 45000c = 720000

$$c=720000\div45000\ =\ 16$$