The table shows the distribution of marks obtained by some candidates in an examination.
Marks |
0-9 |
10-19 |
20-29 |
30-39 |
40-49 |
50-59 |
60-69 |
70-79 |
80-89 |
90-99 |
Frequency |
2 |
6 |
8 |
18 |
28 |
18 |
10 |
6 |
3 |
1 |
(a) (i) Construct a cumulative frequency table for the distribution.
(ii) Use your table in (a)(i) to draw the cumulative frequency curve.
(b) Use your curve in (a)(i) to estimate, correct to one decimal place, the
(i)
upper quartile of the distribution;
(ii)
lowest mark for distinction if 10% of the candidates passed with distinction;
(iii)
probability of selecting a candidate who scored between 52% and 65%.
