Question

The mean of 3, 7, 9, 12, x and 13 is 9. Find x.​

Answer 1

Answer:

This is the answer☺ My dear friend

Step-by-step explanation:

ANSWER

mean=

8

3+7+9+12+13+20+x+y

=10

64+x+y=80

x+y=16 __(I)

variance (σ

2

)=

N

∑(x

1

)

2

−(

x

ˉ

)

2

=

8

9+49+81+144+169+400+x

2

+y

2

−100=25

=852+x

2

+y

2

−800=200

x

2

+y

2

=148 ___(II)

(x+y)

2

=x

2

+y

2

+2xy

(16)

2

=148+2xy

2xy=256−140

xy=

2

108

xy=54