Question

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

Answer 1

Mean = (3*10 + 4*12)/(3+4) = 78/7 = 11.14

Answer 2

Let the three numbers be x, y and z.

It is given that the mean of three numbers is 10.

So we have,

x+y+z/3 =10

x+y+z=30 .....(1)

Let the other four numbers be a, b, c and d

It is given that the mean of other four numbers is 12.

So we have,

a+b+c+d/4=12

a+b+c+d=48 .....(2)


From (1) and (2) the sum of all numbers is,

x+y+z+a+b+c+d=30+48 = 78

the mean of all seven numbers is 78/7 = 11.14