The percentiles provide the age by which a percentage of the population is expected to fail.
Sometimes it may be difficult to determine the best distribution based on the probability plot and goodness-of-fit measures. Use the table of percentiles to compare the percentiles for several selected distributions to see how your conclusions change depending on the distribution chosen.
If several distributions provide a reasonable fit to the data and similar conclusions, then the choice of the distribution is less important.
However, if your conclusions differ depending on the distribution, you may want to report the most conservative conclusion, collect more data, or use additional information, such as process knowledge and expert advice.
Based on a Weibull distribution fitted to the muffler data, 1% of the new type of mufflers are expected to fail by 37265.1 miles.