I'm struggling a little bith in Math. Can someone help me to understand how to calculate MAD (mean absolute deviation)?

It can be calculated by finding the mean of the values first and then find the difference between each value and the mean. Take the absolute value of each difference and find the mean of the difference, which is termed as MAD. Find the MAD of a data set using this mean absolute deviation calculator. MAD Calculator.

Step-by-step explanation:

a 4/6 = 9/12   not proportional

step-by-step explanation:

to find which are not proportional, we can use cross products

if it is true, they are proportional.   if it is not true, they are not proportional.

a 4/6 = 9/12

4* 12 = 6*9

48 = 54

not this is not proportional  

b 2/3 = 12/18  

2* 18 = 3 * 12

36 = 36

this is proportional

c 5/4 = 10/8  

5*8 = 4*10

40 = 40

this is proportional

d 7/5 = 35/25

7*25 = 5 * 35

175 = 175

is proportional