1
Question
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
20 − 30
30 − 40
40 − 50
50 − 60
60 − 70
70 − above
7
10
10
20
20
15
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.
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 20 − 30 30 − 40 40 − 50 50 − 60 60 − 70 70 − above |
7 10 10 20 20 15 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.