For any value, e.g. a, to the nearest x units, the upper and lower bounds are: (a + x/2) and (a - x/2) For your question, there are three dimensions so: Dealing with the first one, we have 24 cm to the nearest 2 cm so the boundaries are: Upper boundary: 24 + 2/2 = 25 Lower boundary: 24 - 2/2 = 23 The second dimension is the same as the first in value and is also given to the nearest 2 cm so the boundaries are the same as for the first. The third dimension is 20 cm to the nearest 2 cm so the boundaries are: Upper boundary: 20 + 2/2 = 21 Lower boundary: 20 - 2/2 = 19
To get the largest possible area, we take the upper bounds of all the dimensions and multiply them so: 25 * 25 * 21 = 13125 cm³
When you plug the numbers in, 4 times 13 = 52+9=61 and 63 is still greate so anything above 13 would make the sentence correct. So that is why 13 is NOT a solution.
