The marks obtained by 90 students of a school in Mathematics out of 100 are given as under:
Marks | 0-20 | 20-30 | 30-40 | 40-50 | 50-60 | 60-70 | 70 and above |
No of students | 7 | 8 | 12 | 25 | 19 | 10 | 9 |
From these students, a students is chosen at random.
What is the probability that the chosen student
(i) gets 20% or less marks?
(ii) gets 60% or more marks?
Total number of students : 90
Number of students who scored less than 20% : 7
Number of students who scored more than 60% : 19
Probability P() = 
(i) Let P(
20) be probability of students who scored less than 20%
P(
20) = 
= 
(ii) Let P(
60) be probability of students who scored more than 60%
P(
60) = 
= 
22