Question

The river flows from west to east and on the way then turns left. After going some distance it encounters a hill. It goes around the hill counter-clockwise in a quarter circle, and then turns right. In which direction is the river finally following?

Accepted Answer

C. 1. Starts West to East (facing East). 2. Turns left $\implies$ facing North. 3. Goes counter-clockwise around hill in a quarter circle $\implies$ turns $90^\circ$ left $\implies$ facing West. 4. Turns right $\implies$ turns $90^\circ$ right $\implies$ facing North... wait, let's re-trace: Start East $\rightarrow$ Turn left (North) $\rightarrow$ Counter-clockwise quarter circle turns direction left by $90^\circ$ to West $\rightarrow$ turn right goes North. But checking standard diagram: From start East, left = North. Circular path around hill CCW quarter circle turns flow from facing North to facing West. Then right turn makes it East? No, North $\rightarrow$ CCW quarter circle turns to West, right turn goes North. Let's look at diagram solution: flows East $\rightarrow$ turns left (North) $\rightarrow$ hill curve CCW quarter circle $\rightarrow$ facing West $\rightarrow$ right turn facin

River direction tracking

Explanation

Practise this under exam conditions