A teacher wanted to analyse the performance of two sections of students in a mathematics test of 100 marks.
A teacher wanted to analyse the performance of two sections of students in a mathematics test of 100 marks. Looking at their performances, she found that a few students got under 20 marks and a few got 70 marks or above. So she decided to group them into intervals of varying sizes as follows: 0 − 20, 20 − 30… 60 − 70, 70 − 100. Then she formed the following table:
| Marks | Number of student |
| 0-20 | 7 |
| 20-30 | 10 |
| 30-40 | 10 |
| 40-50 | 20 |
| 50-60 | 20 |
| 60-70 | 15 |
| 70-above | 8 |
| Total | 90 |
(i) Find the probability that a student obtained less than 20 % in the mathematics test.
(ii) Find the probability that a student obtained marks 60 or above.
1 Answers
Totalnumber of students = 90
(i) Number of students getting less than 20 % marks in the test = 7
Hence, required probability, P = 7/90
(ii) Number of students obtaining marks 60 or above = 15 + 8 = 23
Hence, required probability, P = 23/90