Question

8. If the mean of five observations x,x+2,x+4,x+6,x+8 is 11. Find the mean of first three
observations.
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Answer 1

Answer:

according to question

(x+x+2+x+4+x+6+x+8)/5=11

=> 5x+20=11×5=55

=> 5x=55-20=35

=> x=35/5=7

so mean of the first three observation is

(x+x+2+x+4)/3

=(3x+6)/3

=3(x+2)/3

=x+2

=7+2

=9

Answer 2

Answer:

9

Step-by-step explanation:

sum of observation = x+x+2+x+4+x+6+x+8= 5x + 20

No. of observation = 5

Mean=sum of observation / no. of observation

11 = (5x + 20)/5

5*11. = 5x + 20

55. = 5x + 20

5x = 55 - 20 = 35

x= 35/5=7

putting x value

1st x = 7

2nd x + 2 = 9

3rd x + 4= 11

mean = (7+9+11)/3=9