The average price, or the expected price, of any item in this specialty store is given by the weighted average of each item's price. That is, the sum of the products of each individual price by its corresponding sales mix:
The average price of any item in the store is $7.28
The amount of carrots they each ate are the same because 12 is a multiple of 4. There are 3 4’s in one 12. If you multiply 1/4 times 3 you will get 3/12 because 1 x 3 = 3. And 4 x 3 = 12