Example 2
What are the phone charges for downloading a file from the Internet using a mobile phone under the following conditions?
Please ignore the time required for specifying the file, and for
connecting and disconnecting the line. Also, assume that only
mobile phone fees are incurred for using the Internet connection
service provided by the mobile phone carrier.
Mobile phone fee
: 30 yen per 30 seconds
Communication speed
: 9,600 bits per second
Effective communication
speed
: 80% of communication speed
Size of download file
: 1.2 megabytes (1 byte = 8 bits)
= 9,600,000 bits ÷ 7,680 bits per second
= 1,250 seconds
② Calculation of phone fee
Technology element
1.2 megabytes × 8 bits ÷ (9,600 bits per second × 80%)
(Transmission data volume) (Line transmission speed) (Transmission
efficiency)
Chapter 9
① Calculation of transmission time
1,250 seconds ÷ 30 seconds = 41.666 ···30-second units transmitted 42 times
42 times × 30 yen per 30 seconds = 1,260 yen
Therefore, the phone fee for downloading the file is 1,260 yen.
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