Question

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The mean of three numbers is 12. Two of the numbers are 9 and 14. What is the third number?
* The mean of five numbers is 7. After adding one more number, the mean still remains 7. What
the new number?
% The heights of ten girls were measured in cm and the route are as follows:
Solution​

Answer 1

Step-by-step explanation:

1) mean = (9+14+x) ÷ 3

let x be 3rd number

=> 12 = (23+x) ÷ 3

=> 23+x = 12×3 = 36

=> x = 36-23

=> x = 13

2) mean = (sum of 5 number)÷5

=> 7 = ( sum of 5number ) ÷ 5

=> sum of 5 number = 7×5 = 35......1

let y is new number added

=> (sum of all number ) ÷ 6 = 7

=> ( sum of 5 number + y ) = 7×6

putting value of "sum of 5 number = 35"

=> (35+y) = 42

=> y = 42-35

=> y = 7

so , new number is 7