Waec Model Questions Vol1 2022 Geography Question 40

A region is exposed to three environmental hazards: - Flood (Hazard A): probability $p_A = 0.10$, impact rating $I_A = 9$. - Drought (Hazard B): probability $p_B = 0.15$, impact rating $I_B = 6$. - Landslide (Hazard C): probability $p_C = 0.05$, impact rating $I_C = 7$. Mitigation measures reduce the impacts by 25 % for flood, 15 % for drought and 20 % for landslide. Assuming the hazards occur independently, the annual expected risk index is the sum of $p_i\times I_i'$ for each hazard, where $I_i'$ is the mitigated impact. In addition, if any two hazards occur together in the same year, the combined impact of those two hazards is increased by 20 % of their summed mitigated impacts. Compute the total expected annual risk index, including the synergy effect, and state whether it exceeds the critical threshold of 1.5.