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

Marks
(Class interval) Number of students (Frequency)

1−10 7

11−20 10

21−30 6

31−40 4

41−50 3

One of these students is chosen at random. What is the probability that his marks lie in the interval 21−30?

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Solution

Total number of students = 30
Number of students whose marks lie in the interval 21-30 = 6
Let E be the event that the selected student's marks lie in the interval 21- 30 .

∴ Required probability = P(E) = $\frac{6}{30} = \frac{1}{5} = 0.2$

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Similar questions

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?

Following table gives marks and number of students of a class.

Which point on the frequency polygon will have its y coordinate as 19?

Q. The frequency distribution of marks obtained by students in a class test is given below. Draw frequency polygon and ogive.

Marks	0−10	10−20	20−30	30−40	40−50
Number of Students	5	10	14	10	3

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 following table shows the marks obtained by students of a class in a math test (out of 10 marks). How many students got the least number of marks?

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

The table given below shows the marks obtained by 30 students in a test. Marks (Class interval) Number of students (Frequency) 1−10 7 11−20 10 21−30 6 31−40 4 41−50 3 One of these students is chosen at random. What is the probability that his marks lie in the interval 21−30?

Total number of students = 30 Number of students whose marks lie in the interval 21-30 = 6 Let E be the event that the selected student's marks lie in the interval 21- 30 . ∴ Required probability = P(E) = 630 = 15 = 0.2

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

Marks
(Class interval) Number of students (Frequency)

1−10 7

11−20 10

21−30 6

31−40 4

41−50 3

One of these students is chosen at random. What is the probability that his marks lie in the interval 21−30?

Total number of students = 30
Number of students whose marks lie in the interval 21-30 = 6
Let E be the event that the selected student's marks lie in the interval 21- 30 .

∴ Required probability = P(E) = $\frac{6}{30} = \frac{1}{5} = 0.2$