For number one to find the mean you would first count how many candy bars they have all together and then you would just divide by how many groups there are which since there's four people thats four groups in total they have 44 candy bars because 12+9+10+13=44 which if you divide that by 4 you get 11 as your mean.
For number two you would do the same thing count the total shoe sizes and you should get 40 and since there's 5 people which is five groups it would be 40/5 which means that the total mean would be 8.
You would use the Pythagorem Theory which is a^2 + b^2 = c^2 the diagonal being c and it doesn't matter how you substitute tho other either a or b. the answer is 15.588 or 15.6 inches
