Question

The mean of the obsevation x , 2x+1 , 2x+5 , 2x+9 is 30. what is mean of last two observations

Answer 1

Mean of observations = 30

observations = x , 2x + 1 , 2x + 5, 2x + 9

number of observations = 4

$</p><p> \sf \rightarrow \quad \frac{x + 2x + 1 + 2x + 5 + 2x + 9}{4} = 30 \\ \\ \sf \rightarrow \quad 7x + 15 = 120 \\ \\ \sf \rightarrow \quad 7x = 105 \\ \\ \sf \rightarrow \quad x = 15</p><p>$

Sum of the last two observations = 2x + 5 + 2x + 9

==> 4x + 14

==> 4(15) + 14

==> 60 + 14

==> 74

Mean of last two observations = 74/2

==> 37

Answer 2

Answer:

37

Step-by-step explanation:

add all observation and divide by 4

7x+15/4=30

7x+15=120

7x=120-15

7x=105

x=105/7

x=15

2x+5=2(15)+5

=30+5

=35

2x+9=2(15)+9

=30+9

=39

=35+39/2

=74/2

=37

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