Calculating File Sizes (Cambridge (CIE) O Level Computer Science)

Size of bitmap image = 

Resolution

250,000

Resolution = width x height

Colour Depth

24 bits (3 bytes)

24 bits = 3 bytes

250,000 x 24

=

(bit to bytes) /8

(bytes to KiB) /1024

6,000,000 bits

750,000 bytes

732 KiB

250000 x 3

=

(bytes to KiB) /1024

750,000 bytes

732 KiB

Size of bitmap image = 

Image width

500

Image height

500

Colour Depth

24 bits

24 bits = 3 bytes

(500 x 500 x 24)

=

(bit to bytes) /8

(bytes to KiB) /1024

6,000,000 bits

750,000 bytes

732 KiB

(500 x 500 x 3)

=

(bytes to KiB) /1024

750,000 bytes

732 KiB

Size of sound file = 

Sample rate

100

Samples per second

Duration

60

Seconds

Sample resolution

24

Number of bits stored per sample

100 x 60 x 24

=

(bit to bytes) /8

(bytes to KiB) /1024

144,000 bits

18,000 bytes

18 KiB