Add 100 real numbers, each of which is rounded off to the nearest integer. Assume that each rounding-off error is a random variable uniformly distributed between -½ and ½ and that the 100 rounding-off errors are independent. Find approximately the probability that the error in the sum will be between -3 and 3. Find the quantity A that the probability is approximately 99 % that the error in the sum will be less than A in absolute value.