Question

lf the mean of 3, 7, 11 and x is 9, what is the value of x? ​

Answer 1

Answer:

15

Step-by-step explanation:

mean = average

(3+7+11+x/4)=9

21+x/4=9

21+x = 9×4

21 +x=36

x=36-21

x=15

Answer 2

Given:

• Data are 3, 7, 11 and x
• mean of data is 9

To find :

• Value of x?

Solution:

We are given that mean of data 3,7,11 and x is 9.

We know that :

• $\large{\boxed{\sf{Mean\:=\:\dfrac{sum\:of\: observation}{number\:of\: observation}}}}$

Therefore,

$\large{\sf{Mean\:=\:\dfrac{sum\:of\: observation}{number\:of\: observation}}}$

$\implies\large{\sf{9\:=\: \dfrac{3+7+11+x}{4}}}$

$\implies\large{\sf{9\:=\:\dfrac{21+x}{4}}}$ [shift 21 + x in LHS]

$\implies\large{\sf{21+x\:=\: 9×4}}$

$\implies\large{\sf{21+x\:=\: 36}}$ [shift 21 in RHS]

$\implies\large{\sf{x\:=\: 36 - 21}}$

$\implies\large{\sf{x\:=\: 15}}$

Therefore,

• $\large{\boxed{\sf{Value\:of\:x\:is\:15}}}$

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