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in Mathematics by (3.5k points)

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 Answer

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Best answer

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

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