Question

S3.
In a data set of nine numbers, the mean of the first
three numbers is 8 and that of the last six numbers
is 4. Find the mean of all the numbers.

​

Answer 1

Step-by-step explanation:

Given that

Mean of 3 numbers =10.

⇒10=

3

Sum of 3 observations

⇒ Sum of 3 observation =30...(1)

Also given that

Means of other4 numbers =12

⇒12=

4

Sum of 4 observations

⇒ Sum of 4 observation =48...(2)

From equation (1) and (2), we get

Sum of 7 observation =30+48=78

∴ Mean =

7

78

=11.14

Answer 2

Step-by-step explanation:

Given that

Mean of 3 numbers =10.

⇒10=

3

Sum of 3 observations

⇒ Sum of 3 observation =30...(1)

Also given that

Means of other4 numbers =12

⇒12=

4

Sum of 4 observations

⇒ Sum of 4 observation =48...(2)

From equation (1) and (2), we get

Sum of 7 observation =30+48=78

∴ Mean =

7

78

=11.14