Question

If the mean of 10 observation x ,x + 1 ,X + 2, X + 3 ,X + 4, x + 5 ,x + 6 ,x+ 7, x+ 8 ,x+ 9 is 51 find the mean of first 5 observation

Answer 1

mean of 10 observations=51
X+x+1+x+2+x+3+x+4+x+5+x+6+x+7+x+8+x+9/10=51
10x+45/10=51
10x+45=510
10x=465
X=465/10
X=46.5
mean of first five observations
X+x+1+x+2+x+3+x+4/5=5x+10/5=5(x+2)/5=x+2=46.5+2=48.5

Answer 2

The mean of first 5 observation is 48.5

Step-by-step explanation:

$Mean = \frac{\text{Sum of all observations}}{\text{No. of observations}}$

The mean of 10 observation x ,x + 1 ,X + 2, X + 3 ,X + 4, x + 5 ,x + 6 ,x+ 7, x+ 8 ,x+ 9 is 51

So, $51 = \frac{x+x+1+x+2+x+3+x+4+x+5+x+6+x+7+x+8+x+9}{10}$

$510=x+x+1+x+2+x+3+x+4+x+5+x+6+x+7+x+8+x+9$

$510=10x+45$

$510-45=10x$

$\frac{510-45}{10}=x$

46.5=x

Mean of first five observations=$\frac{x+x+1+x+2+x+3+x+4}{5}=\frac{46.5+46.5+1+46.5+2+46.5+3+46.5+4}{5}=48.5$

Hence the mean of first 5 observation is 48.5

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