Correct Answer - Option 1 : 20
Concept:
Cumulative frequency: Cumulative frequency distribution is the sum of the frequency of class and all classes below it in a frequency distribution.
This means we can get cumulative frequency by adding up a value and all of the values that came before it.
Calculation:
Time is taken (seconds) |
Frequency |
Cumulative frequency |
0 < t ≤ 5 |
2 |
2 |
5 < t ≤ 10 |
9 |
11 |
10 < t ≤ 15 |
9 |
20 |
15 < t ≤ 20 |
8 |
28 |
20 < t ≤ 25 |
3 |
31 |
25 < t ≤ 30 |
1 |
32 |
Clearly, we can see that,
Time by which 28 students had solved the puzzle = 20.