Question

250 students of class X of a school appeared in a test of 100 marks and the data about the marks secured is as below.$$\begin{array}{cccccc}Markssecured& 0-20& 21-40& 41-60& 61-80& 81-100\\ Numberofstudents& 20& 35& 65& 60& 70\end{array}$$

Find the probability of selecting at random, a student who scored

(i) not more than 40
(ii) more than 60
(iii) more than 80 [ 2 MARKS ]

Answer 1

Number of students who didn’t score more than 40 = 20 + 35 = 55
Probability that a student didn’t score more than 40 = $\frac{55}{250}$ = 0.22.
Number of students who scored more than 60 = 60 + 70 = 130
Probability that a student scored more than 60 = $\frac{130}{250}$ = 0.52.

$\left[1Mark\right]$
Number of students who scored more than 80 = 70
Probability that a student scored more than 80 = $\frac{70}{250}$ = 0.28.
$\left[1Mark\right]$