A bridge has an expected life of 25 years and is designed for a flood magnitude of return period 100 years. What is the risk of this hydrologic design ?
1
\(1 - \left( \frac{100}{99} \right)^{25} \)
2
\(\left( \frac{99}{100} \right)^{25} \)
3
\(1 - \left( \frac{99}{100} \right)^{25} \)
4
\(\left( \frac{100} {99}\right)^{25} \)