Question

The mean of three numbers is 10. The mean of other four numbers is 12. Find the mean of all the numbers​ ?​

Answer 1

Answer:

mean of 3 number=10

let the three numbers be x ,y and z.

mean=sum of all observation/total number of observation

10=x+y+z/3

x+y+z=3*10

x+y+z=30

mean of other four numbers=12

let the four numbers be A, B, C and D.

mean=sum of all observation/total number of observation

12=A+B+C+D/4

12*4=A+B+C+D

48=A+B+C+D

Mean of all numbers=sum of all observation/total number of observation

=A+B+C+D+x+y+z/7

=48+30/7

=78/7

=11.14

Answer 2

Answer: 11.15  is the mean of all numbers

Step-by-step explanation:

Given,

Mean of 3 numbers =10.

Then, total of numbers is =10×3=30.

Also, Mean of other 4 numbers is 12.

Then, Total of 4 numbers is =12×4=48.

Therefore, Total  of 4+3=7 numbers is 48+30=78.

We know, Mean find by

Mean= Sum of the elements/Total number of elements

Hence, mean of 7 numbers is  

=78/7

=11.15  is the mean of all numbers