68% of statistics Mean 99 st 95% of statistics Mean 1 st. 1 st. 2 st. dev below 2 st dev above 3 st. dev below dev dev below above Suppose that water usages in American showers are normally distributed, using 15.3 gallons, and a standard deviation of 2.3 gallons. Estimate the pe used (a) % of showers use between 13 and 17.6 gallons. (b) % of showers use more than 22.2 gallons. (c) % of showers use less than 13 gallons. (d) According to the 2 Standard Deviation Rule, data values that are more deviations away from the mean of the distribution are considered to be "u "unusually low." According to this rule, it would be unusual for an America