General Mathematics Paper 2, May/June. 2010
 Questions: 1 2 3 4 5 6 7 8 9 10 11 12 13 Main
General Comments
Weakness/Remedies
Strength

Question 6

(a) The scale of a map is 1:20,000. Calculate the area, in square centimetres, on the map of a forest reserve which covers 85 km²,
(b) A rectangular playing field is 18 m wide. It is surrounded by a path 6m wide such that its area is equal to the area of the path. Calculate the length of the field.

(c]

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Observation

Candidates' performance in part (a) was reported to be poor. A good number of them were reported not to have attempted this part of the question. They were expected to recall that lkm = 100,000 ern, therefore 1km2 = 1km x 1km = 100,000 x 100,000 = 10,000 000,OOOcm2
85km2 = 850,000,000,000 cm². 20,000 em on the ground = 1 cm on the map, hence 400,000,000 cm² on the ground = 1 cm2850,000,000,000 = 2125 cm2 on the map.                                                                                                                                        400,000,000
In part (b), candidates' performance was said to be better than it was in part (a). However, many candidates did not draw the diagram correctly and so were not able to solve the problem.
From the diagram, area of path = 2(30 x 6) + 12a = 360 + 12a. Area of field = 18a. Since they are equal, 18a = 12a + 360. This gave a = 60 m.
In part (c), candidates' performance was described as fair. However, some candidates did not see the reflex angle as 360 - x, hence, did not subtract their final answer from 360° when they had calculated the value of the reflex angle. Here, 360 - x x 22x Z x Z = 27.5 cm2
360         7       2 2

This meant that 360 - x = 360 x 2 x 27.5 from where we obtain x = 103° to the nearest degree
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