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 student is chosen at random- What is the probability that the chosen student i gets 20- or less marks- ii gets 60- or more marks-

You visited us 1 times! Enjoying our articles? Unlock Full Access!

Byju's Answer

Standard IX

Mathematics

Experimental/Empirical Probability

The marks obt...

Question

The marks obtained by 90 students of a school in mathematics out of 100 are given as under:

$\begin{matrix} Marks & 0 - 20 & 20 - 30 & 30 - 40 & 40 - 50 & 50 - 60 & 60 - 70 & 70 and above No. of students & 7 & 8 & 12 & 25 & 19 & 10 & 9 \end{matrix}$

From these students, a student is chosen at random.

What is the probability that the chosen student

(i) gets 20% or less marks?

(ii) gets 60% or more marks?

Open in App

Solution

ANSWER:
Total number of students = 90
(i) Number of students who gets 20% or less marks = Number of students who gets 20 or less marks = 7
∴ P(Student gets 20% or less marks)
= $\frac{Number of students who gets 20% or less marks}{Total number of students} = \frac{7}{90}$
(ii) Number of students who gets 60% or more marks = Number of students who gets 60 or more marks = 10 +9 = 19
∴ P(Student gets 60% or more marks)
= $\frac{Number of students who gets 60% or more marks}{Total number of students} = \frac{19}{90}$

Suggest Corrections

Similar questions

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
Number of students	7	8	12	25	19	10	9

From these students, a student is chosen at random.
What is the probability that the chosen student
(i) gets 20% or less marks?
(ii) gets 60% or more marks?

The table given below shows the marks obtained by 30 students in a test.

$\begin{matrix} Marks & 1 - 10 & 11 - 20 & 21 - 30 & 31 - 40 & 41 - 50 (Class interval) Number of students & 7 & 10 & 6 & 4 & 3 (Frequency) \end{matrix}$

Out of these students, one is chosen at random. What is the probability that the marks of the chosen student

(i) are 30 or less?

(ii) are 31 or more?

(iii) lie in the interval 21-30?

The table given below shows the marks obtained by 30 students in a test.

$\begin{matrix} Marks & 1 - 10 & 1 - 20 & 21 - 30 & 31 - 40 & 41 - 50 (Class interval) Number of students & 7 & 10 & 6 & 4 & 3 (Frequency) \end{matrix}$

Out of these students, one is chosen at random. What is the probability that the marks of the chosen student

(i) are 30 or less?

(ii) are 31 or more?

(iii) lie in the interval 21-30?

Q. The table given below shows the marks obtained by 30 students in a test.

Marks (Class interval)	1 – 10	11 – 20	21 – 30	31 – 40	41 – 50
Number of students (Frequency)	7	10	6	4	3

Out of these students, one is chosen at random. What is the probability that the marks of the chosen student
(i) are 30 or less?
(ii) are 31 or more?
(iii) lie in the interval 21 – 30?

Marks	Number of Students
$0 - 20$	$7$
$20 - 30$	$10$
$30 - 40$	$10$
$40 - 50$	$20$
$50 - 60$	$20$
$60 - 70$	$15$
$70 -$ Above	$8$
Total	$90$

A teacher wanted to analyze the performance of two sections of students in a mathematics test of 100 marks. Looking at their performance, she found that a few students got, under 20 marks and a few got 70 marks or above. So she decided to group them into intervals of varying sizes as follows:

0 - 20, 20 - 30. . . ., 60 - 70, 70 - 100

Then she formed the following table.
(i) Find the probability that a student obtained less than

20

% in the mathematics test.
(ii) Find the probability that a student obtained marks

60

or above.

Join BYJU'S Learning Program