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Solutions to the exercises

Exercise 1

€ 37.49

€ 82.80

$0.8 \cdot 33.50 = 26.80$ ; it is not correct.

Exercise 2

€ 1035.00

€ 1071.23

No, the interest is compounded. The second next year you get interest over the original amount plus the interest from the previous year.

Exercise 3

It makes no difference, for instance $100 \times 0.6 \times 1.21 = 100 \times 1.21 \times 0.6$ .

Exercise 4

$\frac{95}{200} = 0.475$ , so $47.5$ %.

Exercise 5

You get $300$ grams for € 1.75.
If $250$ grams costs € 1.75, $300$ gram should cost $\frac{300}{250} \cdot 1.75 = 2.10$ euro.
Your discount is $0.35$ euro, approximately $16.7$ % of the price.

Exercise 6

$0.35 \cdot 0.40 = 0.14$ , so 14%.

$0.35 \cdot 0.60 = 0.21$ , so 21%.

$\frac{640}{0.14} \approx 4571$ kg.

Exercise 7

$91.281$ mln is 61.93%, so the total population was about $\frac{91.281}{0.6193} \approx 147.394$ mln.

$132187$ km² is 6.95%, so the total surface area was approximately $\frac{132187}{0.0695} \approx$ km².

Sulawesi: $188866$ km² and $10.377$ mln inhabitants.
The remaining islands: $142267$ km²; $7.48$ %; $7.399$ mln inhabitants; $5.02$ %.

Java/Madura: approximately $691$ inhabatants per km².

$\frac{147394000}{} = 77$ inhabitants per km².

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