Refer to Table 14.7, Chapter $ 14 . $
(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.
To do:
We have to find
(i) The probability that a student obtained less than \( 20 \% \) in the mathematics test.
(ii) The probability that a student obtained marks 60 or above.
Solution:
Marks | Number of students |
0-20 | 7 |
20-30 | 10 |
30-40 | 10 |
40-50 | 20 |
50-60 | 20 |
60-70 | 15 |
70-above | 8 |
Total | 90 |
The total number of students $=90$
We know that,
Probability of an event=$ \frac{\text { Number of favourable outcomes }}{\text { Total number of outcomes }}$
Therefore,
(i) Number of students who obtained less than $20 \%$ in the mathematics test $= 7$
This implies,
The probability that a student obtained less than $20 \%$ in the mathematics test $= \frac{7}{90}$
(ii) Number of students who obtained marks 60 or above $= 15+8$
$= 23$
This implies,
The probability that a student obtained marks 60 or above $= \frac{23}{90}$
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