Chapter 7 Decimals Worksheet - New Century Maths Page 33
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38More decimals at work
Example 22
Use the table below to find the cost of a 6-minute phone call made over a distance of
236 km on Friday at 11:00am.
Cost of long-distance phone calls
Approximate cost per minute (rounded to the nearest cent) with a minimum charge of 21c per call.
Under
50 km to
86 km to
166 km to
Over
Distance
50 km
85 km
165 km
745 km
745 km
Day
$0.14
$0.28
$0.35
$0.43
$0.60
8:00am–6:00pm
Monday to Saturday
Night
$0.09
$0.17
$0.26
$0.29
$0.41
6:00pm–10:00pm
Monday to Friday
Economy
6:00pm Saturday
to 8:00am Monday
$0.08
$0.13
$0.18
$0.21
$0.26
10:00pm–8:00am
everyday
Solution
The distance is between 166 km and 745 km so we use the fourth column of costs. The time
is a weekday during daytime, so we use the first row.
The call is charged at $0.43 a minute.
Cost of call = 6 × $0.43
= $2.58
Exercise 7-16
1 Long-distance phone calls
Example 22
Use the table in Example 22 to help you answer these questions:
a Find the cost of a 5-minute call over a distance of 21 km made at 7:45pm on a Tuesday
night.
b Find the cost of an 11-minute phone call from Manly to Penrith (60 km) on a Sunday
morning at 9:30am.
c Janis called her boyfriend Mal, who lives 112 km away, on Saturday night at 6:10pm.
Find the cost of the call if they spoke for an hour-and-a-half.
d A phone call from Sydney to Coffs Harbour (400 km) appeared on the phone bill as a
charge of $2.73. If the call was made on Monday at 10:30pm, work out how long the
call took.
e Make up three questions about phone calls using the table of costs. Work out the
answers and give a classmate the three questions to complete.
230
NEW CENTURY MATHS 7
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