Answer:

Now we can calculate the absolute deviations from the mean for each value:
|0.4-0.4|=0
|0.2-0.4|=0.2
|0.4-0.4|=0
|0.6-0.4|=0.2
And adding these 4 values and dividing by 4we got the MAD on this case:

Explanation:
We have the following dataset given:
0.4,0.2,0.4,0.6
In order to calculate the MAD we need to calculate the sample mean first with this formula:

Replacing we got:

Now we can calculate the absolute deviations from the mean for each value:
|0.4-0.4|=0
|0.2-0.4|=0.2
|0.4-0.4|=0
|0.6-0.4|=0.2
And adding these 4 values and dividing by 4we got the MAD on this case:
