Confidence interval, in statistics can be defined as the probability that a population parameter will fall between two set values( upper and lower bound) for a certain proportion of times. Therefore, there's 99% chance that the true difference in RDI levels between men and women is contained within the 99% Confidence interval shown in the previous questions.
A scale with a suitable range for weighing small items such as food in the home, would not be suitable for weighing large, heavy items, such as concrete blocks. A scale for concrete blocks wouldn't be sensitive enough for food.