I gave this a shot
A.
To calculate the mean (μ): Multiply each value by its probability and add them up.
To calculate the standard deviation (σ): Subtract each value from the mean, square it, multiply it by its probability, add up everything, and take the square root.
To find the range within 3 standard deviations: Multiply the standard deviation by three, then add that number to the mean for the upper bound, and subtract that number from the mean for the lower bound.
B.
To create a cumulative probability distribution: Make flood damage rands the X-Value, and the probability the Y-Value. Put the entire table in order by X-Value (1, 6, 8, 11, 14), then add each probability to the previous one. So 6 has a Y-Value of 0.2 because (0.1 + 0.1). Then 8 has a Y-Value of 0.3 because (0.1 + 0.1 + 0.1).
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