General Mathematics Paper 2,Nov/Dec. 2010
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Question 10

The table gives the distribution of marks for 360 candidates who sat for an examination.

 Marks (%) 0-9 10 - 19 20 - 29 30 -39 40 - 49 50 - 59 60 - 69 70 -79 80 -89 Number of 20 48 60 72 80 40 25 10 5 candidates

(a) Draw a cumulative frequency curve for the distribution.
(b) Use your graph to estimate the semi-interquartile range.
(c) If the minimum mark for distinction is 75%, how many candidates passed with distinction?

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Observation

This question was reportedly very popular among the candidates and their performance was described as fair. Majority of the candidates were reported to have constructed the cumulative frequency table correctly. However, a good number of the candidates used class mid-points or upper class limit rather than upper class boundaries to draw the curve. Candidates should know that cumulative frequency curv,es are drawn using upper class boundaries against the cumulative frequencies. The report also stated that majority of the candidates could not obtain the quartiles from the graph hence could not calculate the semi- interquartile range as required. The inability of candidates to read from their curves was very noticeable