9709 P62 - Jun 2018 - Q5
2391
The lengths, t minutes, of 242 phone calls made by a family over a period of 1 week are summarised in the frequency table below.
| Length of phone call (t minutes) | 0 < t ≤ 1 | 1 < t ≤ 2 | 2 < t ≤ 5 | 5 < t ≤ 10 | 10 < t ≤ 30 |
|---|---|---|---|---|---|
| Frequency | 14 | 46 | 102 | a | 40 |
- Find the value of a.
- Calculate an estimate of the mean length of these phone calls.
- On the grid, draw a histogram to illustrate the data in the table.
