You want to send 10GBytes of videos to a friend. You have a choice of burning them to DVD and sending by express post, which will take 1 day (24 hours) for them to arrive or you can send them by Internet on which you get an average upload data rate of 2Mb/sec. Show which method will be faster. You must show your work, no marks for just guessing an answer.
Try an answer before revealing the guidance below.
Key Concepts
- Bytes vs bits
- Transmission delay
- Upload rate
- Unit conversion
Answer Approach
- Convert the file size from bytes to bits.
- Divide by the upload rate to get the Internet transfer time.
- Convert seconds to hours and compare with 24 hours.
- State any assumption about decimal or binary gigabytes.
Full Answer
Answer status: Draft answer (unofficial). Revision notes, not an official marking scheme.
10 GB = 10 × 2^30 × 8 ≈ 8.59 × 10^10 bits (or 8 × 10^10 bits using decimal GB). At 2 × 10^6 bits/s the upload takes ≈ 42,950 s ≈ 11.9 hours (≈ 40,000 s ≈ 11.1 hours with decimal units). Either way the Internet transfer (about 12 hours) is faster than express post (24 hours), ignoring protocol overhead.
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