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Calculation of data capacity requirements

Introduction
Can you work out the answers to the following data capacity problems? Remember that before you start multiplying and dividing numbers, you always need to make sure they are in the same units i.e. all the numbers are in KB or MB or GB. You don't want to be dividing one number in GB by another number in MB!

MusicExample 1

    • You want to know how many MP3 songs you can store on a CD.
    • A typical song is 4MB.
    • A CD has a capacity of 700 MB.
    • A CD can therefore hold 600 / 4 = 150 songs approximately.

 Example 2

    • You want to know how many MP3 songs you can store on a DVD.
    • A typical song is 4MB.
    • A DVD has a capacity of 4.7 GB.
    • 4.7 GB is 4700 MB.
    • 4700 / 4 = 1175 songs approximately.

FilmExample 3

    • You want to know how many Ultra High Definition films you can burn onto a Blu-ray disk, assuming each film is two hours long and 1 hour takes 7 GB of storage space.
    • A typical film takes 2 * 7 GB = 14GB.
    • A Blu-ray disk has a capacity of 50 GB.
    • 50 /  14 = 3.57
    • You can therefore burn three complete films onto one Blu-ray disk.

 

 

CameraExample 4

    • A professional photographer is using her camera to take high-quality wedding photos. Each photo is approximately 6 MB in size. She has a 64 GB SD card in her camera. How many photos can she take?
    • 64 GB is the same as 64000 MB.
    • 64000 / 6 = 7111
    • She can therefore take aproximately 7100 photos.

Example 5

    • You have set up a free cloud storage account with an online company to save all of your wordprocessed files for school work for the next 2 years. They have given you 5 GB of free storage. Is it enough? You need to know because they keep sending you emails, pressuring you to buy 'extra' storage.
    • You will have to make a few sensible assumptions to do this kind of calculation.
    • A small wordprocessed file with 1 or 2 pages might be about 20 KB. A larger one of 4 pages with a diagram or two might be around 100 KB. A longer project with 20 pages and a few diagrams might be 500 KB but you won't do many of those. On average, we will assume that a wordprocessed document is 100 KB long.
    • 5 GB is the same as 5 000 000 KB.
    • 5 000 000 / 100 = 5000 documents.
    • Over the next two years, you estimate that you will write 10 documents a week, for each of the 40 weeks in each year. That is about 400 documents a year, or 800 documents over 2 years.
    • You have a capacity to write 5000 documents but will only write approximately 800, so your free account should be more than enough for your needs.

Clouds

Example 6

    • You want to transfer your entire music collection held on CDs to Blu-ray disks to save space. You have 400 CDs worth of music. How many Blu-ray disks do you need?
    • A CD holds 700 MB of data.
    • You have 400 CDs so you need to store 400 * 700 = 280 000 MBs of data.
    • A Blu-ray disk holds 50 GB.
    • 50 GB is the same as 50 000 MB.
    • 280 000 / 50 000 = 5.6
    • You therefore need 6 Blu-ray disks to transfer your entire collection.

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