Following table shows the marks scored by a group of 90 students in a mathematics test of 100 marks. Marks 0-20 20-30 30-40 40-50 50-60 60-70 70-100 No. of Students: 7 10 10 20 20 15 8 Find the probability that marks scored by a student in the class is: at most 60 marks             (ii)  at least 60 marks (iii)not more than 50 marks

Explanation

To solve the problem, we will calculate the probabilities for each of the three scenarios based on the given frequency distribution of marks scored by 90 students.

### Given Data:
- **Marks Ranges and Number of Students:**
- 0-20: 7 students
- 20-30: 10 students
- 30-40: 10 students
- 40-50: 20 students
...