1. ## boat speed

a boat is trying to cross a 8km wide lake. the speed of the boat in the first 2 kilometers is unknown but it started to raise it speed 0.5 kilometers per hour faster than the first 2 kilometers. it arrived 10 minutes earlier than expected. find the original speed of the boat.

2. Originally Posted by aeroflix
a boat is trying to cross a 8km wide lake. the speed of the boat in the first 2 kilometers is unknown but it started to raise it speed 0.5 kilometers per hour faster than the first 2 kilometers. it arrived 10 minutes earlier than expected. find the original speed of the boat.
Does this mean that the speed on the last 6km was 1/2 kph greater than on the first 2km?

Let the initial speed be $x$ kph. Then it would have taken $8/x$ hours to cross the lake at that speed. It in fact took $[2/x] + [6/(x+0.5)]$ hours to cross the lake.

Now can you finish?