Page 25 - 新思维数学活动用书7 样章

2 Expressions, formulae and equations

7 Jana uses this formula to work out how much money her friends will
collect from their sponsored walk.

Money collected = distance walked (km) × sponsored rate ($ per km)

How much money do the following friends collect?
a Miriam walks 5 kilometres at a sponsored rate of $16 per

kilometre.
b Yara walks 8 kilometres at a sponsored rate of $18 per kilometre.
8 a Write a formula for the number of hours in any number of
days, using:
i words ii letters

b Use your formula in part a ii to work out the number of hours in
four days.
9 a Use the formula A = bh to work out A when: Tip
i b = 4 and h = 5 ii b = 3 and h = 12 bh means b × h.

b Work out the value of b when A = 52 and h = 4.
10 a Write a formula for the number of hours for any number of
minutes, in:
i words ii letters

b Use your formula in part a ii to work out the number of hours in
360 minutes.
11 Hiroto uses this formula to work out the times it should take him to Tip

travel from his house to any of his friends’ houses.
T = D , where: T is the time, in hours D means D ÷ S.
S S
D is the distance, in kilometres
S is the average speed, in kilometres per hour.
How long does it take Hiroto to travel from his house to:

a Souta’s house, which is 60 kilometres away, at an average speed of
20 kilometres per hour?
b Hina’s house, which is 140 kilometres away, at an average speed

of 40 kilometres per hour?

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