In exams you are often asked to calculate the storage ...

Standard Grade computing Studies- Calculating file sizes

In exams you are often asked to calculate the storage requirements of a graphic or a database file. The basic knowledge needed is an idea of the units used by a computer system and how data is stored.

A bit is a 0 or a 1 1024 bytes = 1 Kb

8 bits (01010101) = 1 byte

1024 Kb = 1 Mb

1024 Mb = 1 Gb

1 pixel in a black and white graphic = 1 bit

a) A black and white logo contains 204800 pixels. What are the storage requirements of the graphic in kilobytes? (2 PS)

b) A black and white logo is 28Kb. How many pixels does it contain? (2 PS)

Resolution/dots per inch are the same as pixels. 1 dot = 1 pixel.

When given a graphic size you must multiply the dpi by each side. The storage requirements for a graphic 4 inches by 5 inches and a dpi (resolution) of 200 would be found by:

4*200*5*200 = 800000 (bits, pixels, dpi) 800000/8 = 100000 (bytes), 100000/1024 (to change to kilobytes) = 97.65625 Kb or 98 Kb

Keep dividing the answer by 1024 until your answer is less than 1024 Round up to whole kilobytes do not round up to whole megabytes.

c) A black and white graphic 3*4 inches has a resolution of 300 dpi. Calculate the storage requirements. Give your answer in the most appropriate units. (3 PS)

d) You have a USB flash drive of 8 Gb how many photographs 100 Kb in size could the drive hold? (2 PS)

e) You have a USB flash drive which has only 3 Mb of storage left and your photographs are 800 * 800 pixels. How many photographs can be stored on the flash drive? (3 PS)

Standard Grade computing Studies- Calculating file sizes

f) A black and white logo contains 356000 pixels. What are the storage requirements of the graphic in kilobytes? (2 PS)

g) A black and white logo is 36Kb. How many bits does it contain? (2 PS)

h) A black and white graphic 2*3 inches has a resolution of 200 dpi. Calculate the storage requirements. Give your answer in the most appropriate units. (3 PS)

i) You have a hard disk drive of 80 Gb how many photographs 1 Mb in size could the drive hold? (PS 2)

j) You have a USB flash drive which has only 5 Mb of storage left and your graphics are 1200 * 600 pixels. How many graphics can be stored on the flash drive? (3 PS)

k) A black and white logo contains 789000 pixels. What are the storage requirements of the graphic in kilobytes? (2 PS)

l) A black and white logo is 48Kb. How many pixels does it contain? (2 PS)

m) A black and white graphic 5*4 inches has a resolution of 350 dpi. Calculate the storage requirements. Give your answer in the most appropriate units. (3 PS)

n) You have a CDR disk which can hold 4 Gb of data, how many photographs 200 Kb in size could the disk hold? (2 PS)

o) You have a USB flash drive which has only 6 Mb of storage left and your photographs are 700 * 500 pixels. How photographs can be stored on the flash drive? (3 PS)

Standard Grade computing Studies- Calculating file sizes

Calculating database file sizes

A bit is a 0 or a 1 1024 bytes = 1 Kb

8 bits (01010101) = 1 byte

1024 Kb = 1 Mb

1024 Mb = 1 Gb

1 character in data file = 1 byte

A data file consists of records, usually one record per person or thing and each record comprises of fields. Each field will contain information. Information will consist of letters and numbers (characters).

Name

Age

Jo Kan

29

Kim Le

32

Tim Fox

55

Height 1.75m 1.66m 1.59m

Telephone 01824561897 01234567891 01478662589

Member. No. 0002 0124 0899

a) A record in a data file contains has four fields, Name, Address, Telephone Number and Post Code. The maximum amount of characters that can be used to store a person's details is 50. How much backing storage would be required to store a data file of 1000 records? (3 PS)

b) The maximum amount of characters that can be used to store the details of one record is 25. How much backing storage would be required to store a data file of 100 records? (3 PS)

c) A USB flash drive has 4 Mb of storage left. If a record in data file needs 3 Kb of storage how many records could be stored on the flash drive? (1 PS)

d) A data file has 200 records. Each record has four fields and each field can contain 10 characters. Calculate the backing storage requirements for this data file. (3 PS)

e) A police data file contains the name, details and a picture of suspects to a recent crime. Each record has 5 fields and each field can contain 40 characters. The pictures used will be no more than 10 Kb. Calculate the storage requirements for a data file of 150 suspects. (4 PS)

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