Question

The numbers 3, 5, 12,15 have frequencies x + 6, x + 2, x - 3 and x respectively. If their mean is 6.67, find the value of x


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Answer 1

Answer:

c

Step-by-step explanation:

Correct option is

C

7

 xf fx  3x 3x  5x+2 5x+10  6x-8 6x-48  4x+6 4x+24 xˉ=n∑fx

where n=The sum of the frequency

Given xˉ=4

∴4ˉ=4x18x−14

⇒16x=18x−14

⇒16x−14x=−14

⇒−2x=−14

⇒x=−2−14=7

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Answer 2

Answer:

Value of x is 3.0468.

Step-by-step explanation:

Given,

xᵢ=3,5,12,15

fᵢ=x+6,x+2,x-3,x

$∑fixi = 3(x + 6) + 5(x + 2) + 12(x - 3) + 15x = 35x +8.......(1)$

and

$∑fi = x + 6 + x + 2 + x - 3 + x = 4x + 5......(2)$

Given Mean

$\frac{∑fixi}{∑fi} = 6.67 \\ \frac{35x + 8}{4x + 5} = 6.67 \\ 35x + 8 = 26.68x + 33.35 \\ 8.32x = 25.35 \\ x = 3.0468$

So value of x is 3.0468.