Find the mean absolute deviation of the set of data 9 12 3 5 8

Step-by-step explanation:

The formula for determining the mean of a data is

Mean = sum of items/number of items

Looking at the given data, sum of the items is

9 + 12 + 3 + 5 + 8 = 37

Number of items = 5

Mean = 37/5 = 7.4

Deviation of each item from the mean is

9 - 7.4 = 1.6

12 - 7.4 = 4.6

3 - 7.4 = - 4.4

5 - 7.4 = - 2.4

8 - 7.4 = 0.6

The sum of the absolute values are

1.6 + 4.6 + 4.4 + 2.4 + 0.6 = 13.6

The mean absolute deviation is

13.6/5 = 2.72

let x and 400 - x be the two numbers.  

==> 0.80x + 0.85(400 - x) = 400 - 68 from the statement of the problem.  

< ==> 0.80x + 0.85(400 - x) = 400 - 68  

==> 340 - 0.05x = 332  

< ==> -0.05x = -8 ==> x = 160, the first number ==> 400 - x = 240, the second number.