1. I think the underlined number is 2. So It will be hundredths.
2. (8 x 100) + (6 x 10) + (3 x 1) + (1/10) + (4/100) + (1/1000)
Or 800 + 60 + 3 + 0.1 + 0.04 + 0.001
-8, 3 Do you need me to explain
The height of the tank must be at least 1 foot, or 12 inches. We know the floor area (which is length x width) must be at least 400 inches. Therefore these minimum dimensions already tell us that the minimum volume is 400 x 12 = 4800 cubic inches. Since we have a maximum of 5000 cubic inches, the volume must be within the range of 4800 - 5000 cubic inches.
We can set the height at exactly 1 ft (or 12 inches). Then we can select length and width that multiply to 400 square inches, for example, L = 40 inches and W = 10 in. This gives us a tank of dimensions 40 x 10 x 12 = 4800 cubic inches, which fits all the criteria.
