Final answer:
Airlines and engineers can use Z-scores to determine the ideal seat width to accommodate 99% of adults by applying statistical methods involving normal distribution.
Step-by-step explanation:
To answer the question about designing airplane seats to fit 99% of adults, one must use the concept of the normal distribution from statistics. The 99th percentile (P99) can be found using the Z-score formula: Z = (X - μ) / σ, where X is the value that corresponds to P99, μ is the mean hip width, and σ is the standard deviation. Having the Z-score that corresponds to the 99th percentile, one can then solve for X, which will provide the hip width that separates the smallest 99% of adults from the largest 1%.