Question

Question

The average of 3 numbers is 15, and the average of 6 other numbers is 12. What is the
average of all 9 numbers?
+
O 11
O 12
O 13
O 15

Answer 1

13

Explanation:

The average of a group of numbers is calculated by adding all of the numbers up and then dividing by the number of numbers. Because of this, we can easily find the sum of the numbers by multiplying the average by the numbers.

1.) The average of the first 3 numbers is 15, meaning that the total of the numbers is 15*3 = 45.

2.) The average of the 6 other numbers is 12, meaning that the total of the numbers is 6*12 = 72.

3.) Since we know the totals of both groups of numbers, to find the total of all the numbers, we add these totals together. 45 + 72 = 117.

4.) Finally, we are finding the average, and since we know the total is 117 and there are 9 numbers, we just divide 117 by 9 to get 13. Therefore, the average of the numbers is 13.

Answer 2

The average of 3 numbers is 15 means, that the value of all three numbers is 45. (Arithmetic mean). The same with 6 other numbers with average of 12 - the sum of them is 12 times 6 = 72. So, the average of all 9 nimbers is (45+72)/9 = 13.