Question

from the data of marks obtained by 20 students of class given in the following frequency table find the mean marks obtained by a student . marks 10,15,20,25 number of students 4, 6,8,2

Answer 1

Total students =20

Freq = 10*4+15*6+20*8+25*2

= 40+ 90 + 160 + 50
= 180+160
= 340

now for mean = total marks obtained / total students

= 340/20 = 17 so mean of all 20 students is 17

hope it helps

Answer 2

Answer:

Step-by-step explanation:

    $f_{i}$                                          $x_{i}$                                              $f_{i}x_{i}$

       10                                          4                                        40

       15                                          6                                        90

      20                                          8                                        160

      25                                          2                                         50

Total student = 30

$\therefore\sum{f}_{i}=20$

$f_{i}x_{i}=40+90+160+50=340$

Mean value

$M=\frac{f_{i}x_{i}}{f_{i}}\\\\\Rightarrow{M}=\frac{340}{20}=17$