Question

Solve the following -

If the mean of the observations x, 2x+1, 2x+5, 2x+9, is 30. What is mean of last two observations ?

Find the mean from the following table-
xi 5 6 7 8 4
fi 3 2 1 3 2
​

Answer 1

Step-by-step explanation:

⇒ ∑x

i

=x+2x+1+2x+5+2x+9=7x+15

⇒ n=4

⇒

x

=30

x

=

n

∑x

i

30=

4

7x+15

120=7x+15

∴ x=15

⇒ After substituting value of x last two numbers become 35 and 39

∴ Mean of last two numbers =

2

35+39

=

2

74

=37