A boat crossed a lake from North to South at the speed of 4 km/h, entered a river and covered twice as much distance going upstream at 3 km/h. It then turned around and stopped at the south shore of the lake. If it averaged 3.2 km/h that day, what was its approximate downstream speed?	Options:
A) 3	B) 5	C) 6	D) 7	E) 8
Another way will be:   Total time for the trip = distance covered in Lake/speed in still water +distance covered upstream/upstream speed + distance covered downstream/downstream speed   If 5D is the total distance, then distance covered in lake = D, distance covered upstream = 2D and distance covered downstream = 2D   =&gt;5D/3.2 = D/4 + 2D/3 + 2D/x (where x is the downstream speed)   =&gt; 5/3.2 = 1/4 + 2/3 +2/x (div. both sides by D)   =&gt; 1.56 = .25+.66 +.65/x =&gt; x=3.09 ~ 3   option 3
<result>A</result>
A boat crossed a lake from North to South at the speed of 4 km/h, entered a river and covered twice as much distance going upstream at 3 km/h. It then turned around and stopped at the south shore of the lake. If it averaged 3.2 km/h that day, what was its approximate downstream speed?