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Date November 2009 Marks available 2 Reference code 09N.1.sl.TZ0.12
Level SL only Paper 1 Time zone TZ0
Command term Find Question number 12 Adapted from N/A

Question

The population of big cats in Africa is increasing at a rate of 5 % per year. At the beginning of 2004 the population was \(10\,000\).

Write down the population of big cats at the beginning of 2005.

[1]
a.

Find the population of big cats at the beginning of 2010.

[2]
b.

Find the number of years, from the beginning of 2004, it will take the population of big cats to exceed \(50\,000\).

[3]
c.

Markscheme

\(10\,000 \times 1.05\)

\( = 10\,500\)     (A1)     (C1)

[1 mark]

a.

\(10\,000 \times {1.05^6}\)     (M1)


Note: Award (M1) for correct substitution into correct formula.


\( = 13\,400\)     (A1)     (C2)

[2 marks]

b.

\(50\,000 = 10\,000 \times 1.05''\)     (M1)(A1)


Note: Award (M1) for \(10\,000 \times 1.05''\) or equivalent, (A1) for \(50\,000\)


\(n = 33.0\) (Accept 33)     (A1)     (C3)

[3 marks]

c.

Examiners report

This question was well answered by many candidates, particularly part (a).

a.

This question was well answered by many candidates, particularly part (a). However, a significant number of students lost a mark for rounding up rather than down in part (b).

b.

This question was well answered by many candidates, particularly part (a). However, a significant number of students lost a mark for rounding up rather than down in part (b). Part (c) proved to be the most difficult both for generating the equation and for solving it.

c.

Syllabus sections

Topic 1 - Number and algebra » 1.8 » Geometric sequences and series.
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