Why compression is needed: less bandwidth

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Quick Questions

Shade in the A or B circle for each question.

1. Why does compressing a file use less bandwidth when it is sent over a network?

A Fewer bits have to be sent

B The bits travel faster along the cable

2. Ten students in a school share one internet connection. Which statement is true?

A Each student gets their own separate bandwidth that others cannot use

B Bandwidth is shared, so smaller files leave more for everyone

3. A video is compressed before it is streamed. What is the benefit?

A It uses less bandwidth, so it is less likely to buffer

B It uses more bandwidth, so the picture is sharper

4. Which is the best description of network congestion?

A A file being compressed to a smaller size

B Too much data trying to use the network at once

5. What effect does compressing many files have on network congestion?

A It reduces congestion

B It increases congestion

Match the Pairs

Draw a line connecting each item on the left to its match on the right.

Left column		Right column
1compression saves bandwidth		ACompression reduces the number of bits in a file. Fewer bits use less bandwidth, not more.
2bandwidth		BBandwidth is shared between users. A compressed file uses less of it and leaves more for others, reducing congestion.
3A video is compressed before streaming, so fewer bits are sent and it plays smoothly without buffering		Csend(compress(file))
4Compressing files before sending them means less congestion because many users share the same network		DThe amount of data that can be sent over a network connection in a given time, shared between all the users.
5Compression makes a file bigger, so it needs more bandwidth to send		Estream(compress(video))
6Only one user can use the bandwidth, so compression has no effect on other users		FA compressed file has fewer bits to send, so it uses less of the shared network bandwidth.

Definitions

compression saves bandwidth

Fill in the Blanks

Complete each line of code by filling in the missing parts.

A compressed file has fewer ____ to send

Bandwidth is ______ between network users

Less data sent means less __________

Streaming video and audio use ___________ so they play without buffering

A compressed file uses ____ bandwidth

Spot the Error

Shade in the letter of the line that contains an error.

Question 1

A IF compressed = TRUE

B bits_sent ← 4000000

C ELSE

D bits_sent ← 8000000

E ENDIF

Question 2

A bandwidth ← 2000000

B size_bits ← 8000000

C IF compressed THEN

D size_bits ← size_bits * 2

E ENDIF

F OUTPUT size_bits / bandwidth

Question 3

A video_bits ← 5000000

B bandwidth ← 2000000

C IF video_bits > bandwidth THEN

D OUTPUT "Video plays"

E ELSE

F OUTPUT "Video plays"

Question 4

A bandwidth ← 100 // Mbps, 4 users

B share ← bandwidth * 4

C OUTPUT share

Question 5

A WHILE streaming = FALSE

B chunk ← compress(chunk)

C SEND chunk

D ENDWHILE

Answer Key

Why compression is needed: less bandwidth

Section A: Quick Questions

A — Fewer bits have to be sent

B — Bandwidth is shared, so smaller files leave more for everyone

A — It uses less bandwidth, so it is less likely to buffer

B — Too much data trying to use the network at once

A — It reduces congestion

Section B: Match the Pairs

compression saves bandwidth → A compressed file has fewer bits to send, so it uses less of the shared network bandwidth.

bandwidth → The amount of data that can be sent over a network connection in a given time, shared between all the users.

A video is compressed before streaming, so fewer bits are sent and it plays smoothly without buffering → stream(compress(video))

Compressing files before sending them means less congestion because many users share the same network → send(compress(file))

Compression makes a file bigger, so it needs more bandwidth to send → Compression reduces the number of bits in a file. Fewer bits use less bandwidth, not more.

Only one user can use the bandwidth, so compression has no effect on other users → Bandwidth is shared between users. A compressed file uses less of it and leaves more for others, reducing congestion.

Section C: Definitions

compression saves bandwidth — A compressed file has fewer bits to send, so it uses less of the shared network bandwidth. This eases congestion and helps video and audio stream smoothly.

Section D: Fill in the Blanks

A compressed file has fewer bits to send

Bandwidth is shared between network users

Less data sent means less congestion

Streaming video and audio use compression
so they play without buffering

A compressed file uses less bandwidth

Section E: Spot the Error

A — An IF statement needs THEN after the condition. The line should be IF compressed = TRUE THEN.

D — Compression should make the file smaller, so the bits to send must be divided, not multiplied. It should be size_bits ← size_bits / 2.

D — If the video needs more bits than the bandwidth can carry, it will buffer. The output should be "Video buffers".

B — Bandwidth is shared between users, so each user gets the total divided by the number of users. It should be share ← bandwidth / 4.

A — The loop must keep compressing and sending while the video is streaming. The condition should be streaming = TRUE.