GATE CS 2017 Set 1 QGA-10 — General Aptitude

A contour line joins locations of equal elevation above mean sea level. A village will get submerged if its elevation is strictly less than the flood water level of $525\text{ m}$.

By analyzing the contour lines (which are spaced at $25\text{ m}$ intervals):

• Village $P$: Located inside the $550\text{ m}$ contour line. $$\text{Elevation}(P) > 550\text{ m} > 525\text{ m} \implies \text{Safe}$$
• Village $Q$: Located between the $525\text{ m}$ and $550\text{ m}$ contour lines. $$525\text{ m} < \text{Elevation}(Q) < 550\text{ m} \implies \text{Safe}$$
• Village $T$: Located between the $500\text{ m}$ and $525\text{ m}$ contour lines. $$500\text{ m} < \text{Elevation}(T) < 525\text{ m} \implies \text{Submerged}$$
• Villages $R$ and $S$: Located outside the $500\text{ m}$ contour line on the lower elevation side. $$\text{Elevation}(R, S) < 500\text{ m} < 525\text{ m} \implies \text{Submerged}$$

Therefore, the villages that get submerged are $R, S, T$.