Kaylee T. answered 05/26/23
Former University and College Math Professor available for tutoring.
The way I see it, when the carts are "nested", they all effectively have a shorter length except for the last one that is sticking out on the end. So,
a) 12 nested carts are equivalent to 11 shortened carts and one full cart. Subtract 3 feet for the one full cart, and the remaining 11 shortened carts have a combined length of 13.75 feet. Divide that by the 11 carts for a per-cart shortened length of 1.25 feet. This means that each cart has the remaining 1.75 feet inside the next cart when they are "nested".
b) A 20-cart stack would be 19 shortened carts plus one full cart, for a total of 19 * 1.25 + 3 = 26.75 feet.
c) Based on the above work, we can say that L = 1.25(n-1) +3 , where n is the number of carts and L is the total length of the nested stack.
d) Set 30 = 1.25(n-1) + 3, so that 27 = 1.25(n-1), and thus n = 22.6, which is NOT a whole number. So, therefore, no number of carts can equal exactly 30 feet in a "nested" arrangement. 22 carts would be shorter (at 29.25 feet) and 23 carts would be too long (at 30.5 feet).