Question

The percentage of marks obtained by a student in monthly unit tests are given below:

$\begin{array}{cccccc}\text{unit test}& I& II& III& IV& V\\ \text{Percentage of marks obtained}& 69& 71& 73& 68& 76\end{array}$

Find the probability that the student gets:

(i) more than 70% marks (ii) less than 70% marks (iii) a distinction.

Answer 1

Percentage of marks obtain in

$\begin{array}{cccccc}\text{unit test}& I& II& III& IV& V\\ \text{Percentage of marks obtained}& 69& 71& 73& 68& 76\end{array}$

(i) Probability of getting more than 70% marks (m)= In unit test II, III,V=3 Total unit test (n)=5

$\therefore$ probability P(A)=$\frac{m}{n}=\frac{3}{5}=0.6$

(ii) Getting less than 70% marks =units test I and IV

$\therefore m=2$

Total unit test (n)=5

$\therefore$ Probablility P(A)=$\frac{m}{n}=\frac{2}{5}=0.4$

(iii) Getting a distinction = In test V (76 of marks)

$\therefore m=1$ Total unit test (n)=5 $\therefore$ Probablility P(A)=$\frac{m}{n}=\frac{1}{5}=0.2$