Question

Find the value of x if the mean of the following data is 9: 12,5,3,18,10,17,x,6,6.Also,find the range of the data.

Answer 1

12+5+3+18+10+17+6+6+x/9=9
77+x=81
X=7
Range =greatest number - smallest number
18-3=15

Answer 2

Hi there!

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What is Mean?

The average of a given set of numbers is called the Arithmetic mean, or simply the mean, of the given numbers.

Mean = $\frac{Sum \: of \: observations }{Number \: of \: observations }$

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Coming to the question ;

Number of observations = 9

Sum of observations

= 12 + 5 + 3 + 18 + 10 + 17 + x + 6 + 6

= 77 + x

Now,


Mean = $\frac{Sum \: of \: observations }{Number \: of \: observations }$

⇒ 9 = $\frac{77 + x }{9}$

⇒ 9 × 9 = 77 + x

⇒ 81 = 77 + x

⇒ x = 81 - 77

⇒ x = 4

Hence, the value of x = 4.


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Range : The difference between the largest and the smallest observation is called the range of the data.

Here, largest observation = 18

And, smallest observation = 3

∴ Range = ( 18 - 3 )

⇒ Range = 15.


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Thanks for the question!

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