Practise Network speeds and transmission time. 12 exam-style questions plus unlimited generated ones on this subtopic, at up to four difficulty levels, with full mark schemes and a progress tracker. Free, no account needed.
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State the unit used to measure the rate at which data is transmitted across a network.
Bits per second
Construct an expression to calculate the time, in seconds, to send the file. You do not need to do the calculation.
250 × 1024 × 1024 × 8 ÷ (20 × 1,000,000)
A 12-megabit file is sent at 4 Mbps. State the time taken to send the file, in seconds.
3 seconds
Sample questions
Written for this site in the style of Edexcel exam questions. They are not taken from real past papers.
Question 1Easy3 marks
(a) State the unit used to measure the rate at which data is transmitted across a network.[1]
(b) State the formula used to calculate the time taken to transmit a file.[1]
(c) A file is 5 bytes long. State the number of bits in the file.[1]
Show the answer and mark scheme
(a)Answer: Bits per second
bits per second (bps)
(b)Answer: time = file size ÷ transmission rate
time = file size ÷ transmission rate (with both in bits or the same units)
(c)Answer: 40 bits
40
Question 2Medium4 marks
A 250 MiB file is sent over a connection with a transmission rate of 20 megabits per second (Mbps). 1 MiB = 1024 × 1024 bytes and 1 megabit = 1,000,000 bits.
(a) Construct an expression to calculate the time, in seconds, to send the file. You do not need to do the calculation.[2]
(b) Give two factors that could make the transfer take longer than your expression suggests.[2]
(b)Answer: Other users sharing the bandwidth; packet headers and resent packets.
other users or devices sharing the connection (congestion)
interference or a weak signal on a wireless connection
extra data such as packet headers and acknowledgements, and lost packets that have to be resent
the server may not be able to send the file at the full rate
the distance or quality of the connection
Question 3Hard5 marks
A video call downloads data at an average rate of 3 megabits per second (Mbps). 1 gigabit = 1000 megabits.
(a) Calculate the amount of data, in megabits, downloaded during a 45-minute video call.[2]
(b) Give your answer to part (a) in gigabits.[1]
(c) The call is made over a home connection with a download speed of 10 Mbps. During the call, another person in the house starts to stream a film that needs 8 Mbps. Explain the effect on the video call.[2]
Show the answer and mark scheme
(a)Answer: 8100 megabits
45 × 60 = 2700 seconds
3 × 2700 = 8100 (megabits)
(b)Answer: 8.1 gigabits
8.1 (gigabits)
(c)Answer: They need 11 Mbps in total but only 10 Mbps is available, so the call gets too little data and freezes or loses quality.
together they need 3 + 8 = 11 Mbps, which is more than the 10 Mbps available / the bandwidth is shared between the two devices
so the call does not receive enough data each second and may freeze, lag or drop in quality