Hello!
The mean is kind of like the mean of the mean. First let's find the mean of the 7th grade. We add up all the numbers and divide by the number of numbers.
0,0,0,0,0,0,0,1,1,1,1,1,1,2,2,2,2,2,2,2,3,3,3,3,3,4,4,4,4,5,5,6=67
67/32≈2.09
Now we need to see how how far each number in the data set is from 2.09. As we would like to make it a bit simpler so we don't have to do a ton of subtracting we will just round it to 2.Then we add up all of the numbers we get and divide by 32.
2,2,2,2,2,2,2,1,1,1,1,1,1,0,0,0,0,0,0,0,0,1,1,1,1,1,2,2,2,2,3,3,4=43
43/32≈1.34
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As you can see how to find the mean and mean absolute deviation I will just show the answers for 8th grade below.
Mean≈3.4
Mean absolute deviation≈1.4
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As you can see, the mean and MAD of each grade are shown below.
7th Mean≈2.09
8th Mean:3.4
7th MAD:1.34
8th MAD:1.4
For the first option, the mean of the 7th grade pets is about 1.4 less than 8th grade.
For the second, this distance is about the same as the MAD of each data set.
I hope this helps!