Mark the missing value of the following data. Mean marks are 11.66.

Weekly Wages 5 6 7 8 12 ? 15 17 18

Frequency 3 10 5 10 12 15 11 13 1

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Solution

Marks
(x) Frequency
(f) fx

5
6
7
8
12
x
15
17
18 3
10
5
10
12
15
11
13
1 15
60
35
80
144
15x
165
221
18

Σf = 80 Σfx = 738 + 15x

$X = \frac{Σ f x}{Σ f} or, 11.66 = \frac{738 + 15 x}{80} or, 932.8 = 738 + 15 x or, 932.8 - 738 = 15 x or, 194.8 = 15 x or, x = \frac{194.8}{15} \Rightarrow x = 12.99 or 13 (approximately)$

So, the missing weekly wage is Rs 13.

Suggest Corrections

Class Interval	11−13	13−15	15−17	17−19	19−21	21−23	23−25
Frequency	3	6	9	13	?	5	4

Weekly Wages	40−43	43−46	46−49	49−52	52−55
Frequency	3	6	9	13	?

Wages (₹)	0−5	5−10	10−15	15−20	20−25	25−30
Number of Workers	4	6	3	8	12	7