MAX/MIN Differentiation (1 Viewer)

[sleepyair]

A man in a rowing boat is presently 6km from the nearest point A on the shore. He wants to reach as soon as possible a point B that is a further 20km down the shore from A. If he can row at 8km/hr and run at 10km/hr, how far from A should be land?

From Cambridge Year 11 3unit 10H Question 26

 

[IceKool15]

He should row 8km from A to be land.

 

[sleepyair]

Nice job, could you explain to me how you did it? Maybe attach a picture? I can't interpret the question properly.