The grouped frequency table below shows the times taken for 70 students to solve a prob. (Table: Time (t minutes) | 0 < t ≤ 3 | 3 < t ≤ 4 | 4 < t ≤ 5 | 5 < t ≤ 6 | 6 < t ≤ 8 Number of students | 24 | 12 | 16 | 10 | 8)

1. (a)Complete the cumulative frequency table for this information. (Table: Time (t minutes) | t ≤ 3 | t ≤ 4 | t ≤ 5 | t ≤ 6 | t ≤ 8 Number of students | 24 | (empty) | (empty) | (empty) | (empty))[1]
2. (b)In which group of the frequency table does the 40th percentile lie?[1]
3. (c)Complete the frequency density table for this information. (Table: Time (t minutes) | 0 < t ≤ 3 | 3 < t ≤ 4 | 4 < t ≤ 5 | 5 < t ≤ 6 | 6 < t ≤ 8 Frequency density | 8 | 12 | 16 | (empty) | (empty))[2]