Question

17) Marks scored
marks scored:20 25 28 29 33 38 42 43
no. of students:6 20 24 28 15 4 2 1
No. of students
a)
Find the probability of the students getting more than 40 marks.
b)
Find the probability of the students getting less than 30 marks.
​

Answer 1

$\textbf{Given:}$

$\left\begin{array}{|r|c|c|c|c|c|c|c|c|}\cline{1-9}\textbf{Marks scored}&20&25&28&29&33&38&42&43\\\cline{1-9}\textbf{No.of students}&6&20&24&28&15&4&2&1\\\cline{1-9}\end{array}\right$

$\text{Total no. of students n(S) =100}$

$\textbf{Formula used}$

$\text{The probability of an event E is}$

$\bf\,P(E)=\frac{\textbf{Nmber of ways favourable to E}}{\textbf{Total number of ways}}$

$\implies\boxed{\bf\,P(E)=\frac{n(E)}{n(S)}}$

$\text{Let A be the event of scoring more than 40 maarks}$

$\text{Then, n(A)=3}$

$P(A)=\frac{n(A)}{n(S)}$

$\bf\,P(A)=\frac{3}{100}$

$\therefore\textbf{The probability of students getting more than 40 marks is \bf\frac{3}{100} }$

$\text{Let B be the event of scoring less than 30 maarks}$

$\text{Then, n(B)=78}$

$P(B)=\frac{n(B)}{n(S)}$

$P(B)=\frac{78}{100}$

$\bf\,P(B)=\frac{39}{50}$

$\therefore\textbf{The probability of students getting less than 30 marks is \bf\frac{39}{50} }$

Answer 2

Given :  Marks Scored by Students

To find : probability of the students getting more than 40 marks. and less than 30 marks.

Solution:

Marks      number of students

20                     6

25                     20

28                     24

29                     28

33                     15

38                     4

42                     2

43                     1

Total             100

students getting more than 40 marks. =  Getting Marks 42 & 43

= 2 + 1

= 3

Probability of the students getting more than 40 marks. = 3/100

students getting less than 30 marks. = Getting Marks  20 , 25 , 28 , 29

= 6 + 20 + 24 + 28

= 78

probability of the students getting less than 30 marks. = 78/100

= 39/50

​

Probability of the students getting more than 40 marks. = 3/100

probability of the students getting less than 30 marks. = 39/50

Learn more:

if two dice are tossed, find the probability of throwing a total of 10 or ...

https://brainly.in/question/7714685

​

If you flip three fair coins, what is the probability that you'll get all ...

https://brainly.in/question/7633345

In a Family of 3 children find probability of having at least one boy ...

https://brainly.in/question/7700718