So Mean Absolute Deviation or MAD for short is the Mean of how far each digit is from the Mean. So first find the mean, then for each number so let's say the mean is 3 and the numbers are 2, 4, 3. So 3-2=1, 4-3=1, 3-3=0. So you have 1, 1, 0. Find the mean of that 1+1+0=2/3 so the MAD is 2/3.
So just follow my steps 1. Find the mean 2. Find the difference from the mean of each number 3. Find the mean of step 2 4. Step 3 is your answer
10 feet 6 inches = 126 inches. Length of the car is 126 inches and the model length is 7 inches. 126 : 7 = 18 The scale factor of the model to the actual car is 1 : 18.