Donald duck can can swim his pool downstream(with the pool current helping time) in exact 40 seconds and upstream(against the pool current) in a pool in exact 60 seconds. The length of pool is 2 kilometers.
How long Donald duck can cover distance of one side at a still pool (with no current). Choose one.
A) 44 minutes	B) 45 minutes	C) 43 minutes	D) 48 minutes	E) 50 minutes
D   48 minutes.   48 minutesonald duck's speed = X km/seconds   pool current speed = Y km/seconds   2/(X+Y) = 40   2/(X-Y) = 60   Solving the simultaneous equations gives X = 1/24   Therefore, to cover 2km will take 2/X = 48 seconds
<result>D</result>
Donald duck can can swim his pool downstream(with the pool current helping time) in exact 40 seconds and upstream(against the pool current) in a pool in exact 60 seconds. The length of pool is 2 kilometers.
How long Donald duck can cover distance of one side at a still pool (with no current).