Question

The probability of a 10 year flood to occur atleast once in the next 4 years is

• A. 45%
• B. 35%
• C. 30%
• D. 20%

Answer 1

The correct option is B 35%

Probability of an event occurring atleast once in 'n' successive years is called risk:
$Risk=1-\left(q^n\right)=1-{(1-\frac{1}{T})}^n=1-{(1-\frac{1}{10})}^4$
$=0.35or35\%$