The mean of following frequency distribution is . Find the value of 'f'. Class interval | Frequency ----- | ----- 0 - 10 | 8 10 - 20 | 22 20 - 30 | 31 30 - 40 | f 40 - 50 | 2

Class interval | Class mark (x) | Frequency (f) | fx ----- | ----- | ----- | ---- 0 - 10 | 5 | 8 | 40 10 - 20 | 15 | 22 | 330 20 - 30 | 25 | 31 | 775 30 - 40 | 35 | f | 35f 40 - 50 | 45 | 2 | 90 Total | | Σf = 63 + f | Σfx = 1235 + 35f By formula, Mean = Hence, f = 7.

Mathematics

The mean of following frequency distribution is $21\dfrac{1}{7}$ . Find the value of 'f'.
Class interval Frequency
0 - 10 8
10 - 20 22
20 - 30 31
30 - 40 f
40 - 50 2

Class interval	Frequency
0 - 10	8
10 - 20	22
20 - 30	31
30 - 40	f
40 - 50	2

Measures of Central Tendency

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Answer

Class interval	Class mark (x)	Frequency (f)	fx
0 - 10	5	8	40
10 - 20	15	22	330
20 - 30	25	31	775
30 - 40	35	f	35f
40 - 50	45	2	90
Total		Σf = 63 + f	Σfx = 1235 + 35f

By formula,

Mean = $\dfrac{Σfx}{Σf}$

$\Rightarrow 21\dfrac{1}{7} = \dfrac{1235 + 35f}{63 + f} \\[1em] \Rightarrow \dfrac{148}{7} = \dfrac{1235 + 35f}{63 + f} \\[1em] \Rightarrow 148(63 + f) = 7(1235 + 35f) \\[1em] \Rightarrow 9324 + 148f = 8645 + 245f \\[1em] \Rightarrow 245f - 148f = 9324 - 8645 \\[1em] \Rightarrow 97f = 679 \\[1em] \Rightarrow f = \dfrac{679}{97} = 7.$

Hence, f = 7.

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Marks	No. of boys
30 - 40	10
40 - 50	12
50 - 60	14
60 - 70	12
70 - 80	9
80 - 90	7
90 - 100	6

C.I.	Frequency
63 - 70	9
70 - 77	13
77 - 84	27
84 - 91	38
91 - 98	32
98 - 105	16
105 - 112	15

Class	Frequency
0 - 20	7
20 - 40	p
40 - 60	10
60 - 80	9
80 - 100	13

Mathematics

The mean of following frequency distribution is $21\dfrac{1}{7}$ . Find the value of 'f'.
Class interval Frequency
0 - 10 8
10 - 20 22
20 - 30 31
30 - 40 f
40 - 50 2

Measures of Central Tendency

Answer

Related Questions

The following are the marks obtained by 70 boys in a class test.
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70 - 80 9
80 - 90 7
90 - 100 6
Calculate the mean by :
(i) Short-cut method
(ii) Step-deviation method

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C.I. Frequency
63 - 70 9
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77 - 84 27
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Mathematics

The mean of following frequency distribution is 211721\dfrac{1}{7}2171​. Find the value of 'f'.Class intervalFrequency0 - 10810 - 202220 - 303130 - 40f40 - 502

Measures of Central Tendency

Answer

Related Questions

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Find mean by 'step-deviation method' :C.I.Frequency63 - 70970 - 771377 - 842784 - 913891 - 983298 - 10516105 - 11215

Using the information given in the adjoining histogram; calculate the mean.

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The mean of following frequency distribution is $21\dfrac{1}{7}$ . Find the value of 'f'.
Class interval Frequency
0 - 10 8
10 - 20 22
20 - 30 31
30 - 40 f
40 - 50 2

The following are the marks obtained by 70 boys in a class test.
Marks No. of boys
30 - 40 10
40 - 50 12
50 - 60 14
60 - 70 12
70 - 80 9
80 - 90 7
90 - 100 6
Calculate the mean by :
(i) Short-cut method
(ii) Step-deviation method

Find mean by 'step-deviation method' :
C.I. Frequency
63 - 70 9
70 - 77 13
77 - 84 27
84 - 91 38
91 - 98 32
98 - 105 16
105 - 112 15

If the mean of the following observations is 54, find the value of p.
Class Frequency
0 - 20 7
20 - 40 p
40 - 60 10
60 - 80 9
80 - 100 13