Data accumulated by Environment Canada show that the average wind speed in kilometres per hour for Victoria International Airport, located on the Saanich Peninsula in British Columbia, is 9.3. Suppose wind speed measurements are normally distributed for a given geographic location. If22.45% of the time the wind speed measurements are more than18.0km/h, what is the standard deviation of wind speed at Victoria International Airport?

(Round value of z to 2 decimal places, e.g. 0.75. Round your answer to 1 decimal place, e.g. 15.7.)