This week the topic was quadratic equations and their applications. We interviewed Colin Wright, who works on radar systems for coordinating and tracking ships and boats.
Puzzle: A boat is going to sail 20km upstream along a river, then 20km back to where it started. Due to the speed of water flowing in the river, its speed is reduced by 2kph on the way upstream and increased by 2kph on the way downstream.
If the speed of the boat’s engine is x (kph), this means it travels 20km at (x-2)kph and then 20km at (x+2)kph. The total journey needs to take 3.5 hours. What value of x does the boat driver need to use?