Following frequency distribution gives the weights of 40 students of a class .

A student from the class is chosen at random . What is the probability that the weight of the chosen student is
(i) at most 60 kg (ii) at least 56 kg (iii) not more than 50 kg ?

Explanation

Total number of students = 40.
(i) Let `E_(1)` be the event of choosing a student whose weight is at most 50 kg . Then ,
P(choosing a student whose weight is at most 60 kg)
= `P(E_(1))`
`= ("number of students whose weight is 60 kg or less")/("total number of students")`
`= (10 + 6 + 14 + 4 + 1 + 1)/(40) = (36)/(40) = (9)/(10)`.
(ii) Let `E_(2)` be the event of choosing a student whose weight is at least 56 kg . then ,
P(choosing a student whose weight is at least 56 kg)
`= P(E_(2))`
=`("number of students whose weight is 56 kg or more")/("total number of students")`
`= (1 + 2 + 1+ 1)/(40) = (5)/(40) = (1)/(8)` .
(iii) Let `E_(3)` be the event of choosing a student whose weight is not more than 50 kg . then ,
P(choosing a student whose weight is not more than 50 kg)
`= P(E_(3))`
`= ("number of students whose weight is 50 kg or less")/("total number of students")`
`= (10 + 6 + 14+ 4)/(40) = (34)/(40) = (17)/(20)`.