Question

find the mean of 30 member, given that the mean of 10 of them is 12 and mean of remaining 20 is 9​

Answer 1

Answer:

10.hope this helps u

Step-by-step explanation:

mean of ten no:s is 12. If s1 is the sum if these ten numbers, then:

mean of ten numbers= 12

s1/10 = 12

so, s1 = 12*10

s1= 120

mean of remaining twenty no:s is 9. If s2 is the sum if these twenty numbers, then:

mean of twenty numbers= 9

s2/20 = 9

so, s2 = 9*20

s2= 180

Therefore:

mean of the 30 numbers

= sum of the 30 no:s/30

=(s1 + s2) / 30

= (120 + 180) / 30

= 300 / 30

= 10

The answer is 10