Question

Find the mean of 30 numbers given tgat of the first 10 numbers mean is 12 and remaining 20 of mean is 9

Answer 1

Answer:

19 is the mean of 30 numbers

Answer 2

Answer:

mean of all 30 numbers will be 10

Step-by-step explanation:

for first 10

Mean = sum of observation÷ number of observation

as mean of first 10 number = 12

so, 12 = sum of observation÷ 10

now, 12×20 = sum of observation

sum of first 10 observation = 120

same as above

for next remaining 20

9 = sum of observation÷20

9×20 = sum of observation

sum of observation for remaining 20 = 180

now mean for whole 30

sum of observation of all 30÷ 30

sum of observation of all 30 = sum of first 10+ sum of remaining 20 = 120+180= 300

mean = 300 ÷ 30

mean for all 30 = 10