Math, asked by jiya1916, 2 months ago

there are three section of class 10th in Kendriya Vidyalaya Delhi Cantt the total number of strain in class 10th 400 the marks obtained by the students in pre board exam are presented in the table as given below the mean of the marks obtained in 53
Marks obtained=0-20,20-40,40-60,60-80,80-100
Number of student 15,18,21,29,p
(1) how many students got marks between 80-100?
a)21 (b)38 (c) 17 (d)26 (2) what is the lower limit of modal class a)20 (b)40 (c)60 (d) 80 (3) what is the value of modal marks
(a)58 (b)62 (c) 65 (d) 68 (4) what is the value of {fixi? (a)2900 (b) 5300 (c) 1500 (d) 100
(5) what is the upper limit of the median class?
(a) 20 (b) 40 (c) 60 (d) 80

Answers

Answered by amitnrw
10

Given :

Marks obtained=   0-20,20-40,40-60,60-80,80-100

Number of student   15  ,  18,       21,       29,        p

mean of the marks obtained is 53

To Find  : (1) how many students got marks between 80-100?

a)21 (b)38 (c) 17 (d)26 (2)

what is the lower limit of modal class a)20 (b)40 (c)60 (d) 80  

what is the value of modal marks

(a)58 (b)62 (c) 65 (d) 68  

what is the value of {fixi? (a)2900 (b) 5300 (c) 1500 (d) 100

what is the upper limit of the median class?

(a) 20 (b) 40 (c) 60 (d) 80

Solution:

Marks obtained class mark x         f             fixi

0-20,                       10                    15            150          

20-40,                    30                    18            540    

40-60,                    50                    21           1050    

60-80,                    70                    29          2030    

80-100                   90                    p             90p

                          Total                  83+p        3770 + 90p

Mean = (3770 + 90p)/(83   + p)  = 53

=> 3770 + 90p = 83 * 53 + 53p

=> 37p  = 629

=> p = 17

17 students got marks between 80-100

Modal class 60-80   with f = 29

lower limit of modal class 60

Mode = 60 + 20 * (29 - 21)/(29 - 21 + 29 - 17)

= 60 + 20 * 8/20

= 68

value of modal marks = 68  

∑fixi  =  3770 + 90p  = 3770 + 90(17) = 5300

83 + p = 83 + 17 = 100

100/2 = 50

15 + 18 + 21 = 54 > 50

Median class = 40-60

upper limit of the median class 60

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Answered by anshugang
4

Answer:

arks obtained=   0-20,20-40,40-60,60-80,80-100

Number of student   15  ,  18,       21,       29,        p

mean of the marks obtained is 53

To Find  : (1) how many students got marks between 80-100?

a)21 (b)38 (c) 17 (d)26 (2)

what is the lower limit of modal class a)20 (b)40 (c)60 (d) 80  

what is the value of modal marks

(a)58 (b)62 (c) 65 (d) 68  

what is the value of {fixi? (a)2900 (b) 5300 (c) 1500 (d) 100

what is the upper limit of the median class?

(a) 20 (b) 40 (c) 60 (d) 80

Solution:

Marks obtained class mark x         f             fixi

0-20,                       10                    15            150          

20-40,                    30                    18            540    

40-60,                    50                    21           1050    

60-80,                    70                    29          2030    

80-100                   90                    p             90p

                         Total                  83+p        3770 + 90p

Mean = (3770 + 90p)/(83   + p)  = 53

=> 3770 + 90p = 83 * 53 + 53p

=> 37p  = 629

=> p = 17

17 students got marks between 80-100

Modal class 60-80   with f = 29

lower limit of modal class 60

Mode = 60 + 20 * (29 - 21)/(29 - 21 + 29 - 17)

= 60 + 20 * 8/20

= 68

value of modal marks = 68  

∑fixi  =  3770 + 90p  = 3770 + 90(17) = 5300

83 + p = 83 + 17 = 100

100/2 = 50

15 + 18 + 21 = 54 > 50

Median class = 40-60

upper limit of the median class 60

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