Question

if the mean of five number is 10 and the mean of other 15 number is 20 what is the combined mean of both​

Answer 1

Given ;

Mean of five numbers = 10

let sum of that 5 numbers be x

then , mean : x/5 = 10

x = 10×5

(sum of 5 numbers)x = 50

Mean of other 15 numbers = 20

let sum of that 15 numbers be y

then , mean : y/15 = 20

y = 20 × 15

(sum of 15 numbers )y = 300

so, mean of both these will be

sum of all observations/no. of observations

( 50 + 300 ) / 20

350/20

17.5

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