Engineers want to design seats in commercial aircraft so that they are wide enough to fit​ 99% of all adults.​ (Accommodating 100% of adults would require very wide seats that would be much too​ expensive.) Assume adults have hip widths that are normally distributed with a mean of 13.6 in. and a standard deviation of 1.11 in. Find P99. That​ is, find the hip width for adults that separates the smallest​ 99% from the largest​ 1%.

Features Features Normal distribution is characterized by two parameters, mean (µ) and standard deviation (σ). When graphed, the mean represents the center of the bell curve and the graph is perfectly symmetric about the center. The mean, median, and mode are all equal for a normal distribution. The standard deviation measures the data's spread from the center. The higher the standard deviation, the more the data is spread out and the flatter the bell curve looks. Variance is another commonly used measure of the spread of the distribution and is equal to the square of the standard deviation.