Question

When designing roads, buildings, and bridges in a floodplain, engineers consider the statistical probability of a flood of a given size happening in a given year. A 50-year flood has a ____ probability of occurring in a given year

Answer 1

1/50

Step-by-step explanation:

You want to know the probability in any given year of a "50-year flood."

Flood probability

A "50-year flood" is one that occurs once in 50 years, on average. Its probability in any given year is 1/50.

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Additional comment

Weather and climate statistics have been gathered over a period of relatively benign weather, namely the last 150 years or so. As they say in the financial markets, "past performance may not be indicative of future results."

Recent instances of "200-year" and "1000-year" floods occurring relatively close together in time suggest that engineering guidelines will need to be changed.