9709 P61 - Jun 2014 - Q7
2400
A typing test is taken by 111 people. The numbers of typing errors they make in the test are summarised in the table below.
| Number of typing errors | 1–5 | 6–20 | 21–35 | 36–60 | 61–80 |
|---|---|---|---|---|---|
| Frequency | 24 | 9 | 21 | 15 | 42 |
- Draw a histogram on graph paper to represent this information.
- Calculate an estimate of the mean number of typing errors for these 111 people.
- State which class contains the lower quartile and which class contains the upper quartile. Hence find the least possible value of the interquartile range.
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