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Solutions to the exercises

Exercise 1
a

f ( 4 ) = 122880

b

x = ( 20000 120 ) 1 5 2 . 78

c

By 4 5 = 1024

Exercise 2
a

0.01

b

r = 10 gives s 2 = 1000 and therefore s 31.6 km/h.

c

s = 10 r
So s is directly proportional to s 1 2 .

d

If r = 100 , then s = 10 100 = 100 km/h. If r = 50 , then s = 10 50 70,7 km/h. The statement is false.

Exercise 3
a

V ( 2 ) = 2 3 = 8 cm3.
V ( 6 ) = 6 3 = 216 cm3.

b

The volume is 3 3 = 27 times larger.

c

r 3 = 50 , so r = 50 3 3.7 cm.

d

V = r 3

e

r = V 3

Exercise 4
a

Own answer.

b

A ( 3 ) = 54 cm2 and A ( 6 ) = 216 cm2.

c

The surface area becomes 4 times as large.

d

r = 500 6 9.13 cm.

e

r = A 6

Exercise 5
a

G = 7.9 r 3

b

A = 6 r 2

c

From G = 7.9 r 3 follows r = ( 1 7.9 ) 1 3 G ( 1 3 ) 0.502 G 1 3 .
Therefore A = 6 r 2 6 0.502 2 G ( 2 3 ) 1 , 51 G 2 3 and c 1.51 .

d

Do it.

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