In the following question, the sentence given with blank to be filled in with an appropriate word. Select the correct alternative out of the four and indicate it by selecting the appropriate option.
A helicopter flies 80 km North, then it turns West and flies 50 km, then it turns North and flies 120 km, then it turns to its right and flies 50 km. Where is it now with reference to its starting position?
A boat goes 15 km upstream and 10 1/2 km down stream in 3 hrs 15 min. It goes 12 km upstream and 14 km downstream in 3 hrs. What is the speed of the boat in still water?