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.
Answers
Answer:
7/90
23/90
Step-by-step explanation:
Marks Frequency Less than frequency Greater thah frequency
0-20 7 7 90
20-30 10 17 83
30-40 10 27 73
40-50 20 47 63
50-60 20 67 43
60-70 15 82 23
70-100 8 90 8
probability that a student obtained less than 20 % in the mathematics test
= 7/90
the probability that a student obtained marks 60 or above. = 23/90