Question

The table given below shows the marks obtained by 80 students of a class in a test with maximum marks 10
Marks
0-15 15-30
30-45
45-60
60-75 above 75
No. of students
16
13
17
24
1
A student of the class is selected at random. Find the powobability
(i) less than 15% marks (ii) 60 or more marks (iii) less than 45 marks​

Answer 1

Answer:

(i) 0.2

(ii) 0.125

(iii) 0.575

Step-by-step explanation:

We are the following table that shows the marks obtained by 80 students of a class in a test with maximum marks 100;

         Marks                          No. of students

          0 - 15                                    16

         15 - 30                                   13

         30 - 45                                   17

         45 - 60                                   24

         60 - 75                                     1

         75 - 100                                  9          

                                                 Total = 80    

(i) Probability that student scored less than 15% marks is;

Firstly 15% Marks = 15% of 100 = 15 marks

So, Number of students who scored less than 15 marks are 16 out of total of 80 students.

Therefore,  Probability that student scored less than 15% marks = $\frac{16}{80}$ = 0.2

(ii) Probability that student scored 60 or more marks is;

 Number of students scoring 60 or more marks = 1 + 9 = 10

So, required probability = $\frac{10}{80}$ = 0.125

(iii) Probability that student scored less than 45 marks is;

 Number of students scoring less than 45 marks = 16 + 13 + 17 = 46

So, required probability = $\frac{46}{80}$ = 0.575 .

       

                                           

Answer 2

Answer:

Total number of students = 80 . <br> (i) P(The student gets less than 15% marks) <br> =

("number of students getting less than 15 marks")/("total number of students")

<br>

= (6)/(80) = (3)/(40)

. <br> (ii) P(The student gets 60 or more marks) <br>

= ("number of students getting 60 or more marks")/("total number of students")

<br> =

(16 + 4)/(80) = (20)/(80) = (1)/(4)

. <br> (iii) P(The student gets less than 45 marks ) <br> =

("number of students getting less than 45 marks")/("total number of students")

<br>

= (6 + 13 + 17)/(80) = (36)/(80)= (9)/(20).