







Find the speed of the current of the river 
20100519 

From paul: a boat travels 100 miles downstream in the same length of time it travels 50 miles upstream. if the boat's speed in still water is 30 mph find the speed of the current of the river? Answered by Penny Nom. 





Paddling downstream 
20090904 

From Nicole: You head downstream on a river in a canoe. You can paddle at 6 km/h and the river is flowing at 2.4 km/h. How far downstream will you be in 55 minutes? Answered by Penny Nom. 





Moving grain across the river 
20080312 

From Janice: Wesley needs to move 820 kg of grain across the river in a canoe that can carry no more than 120 kg. Wesley has a mass of 70 kg. What is the fewest number of trips he will have to make? A. 17 trips; B. 18 trips; C. 32 trips; D. 33 trips. Answered by Penny Nom. 





Velocity 
20070404 

From Jessica: The speed of the current in a river is 2mph. Jessica travels 20 miles upstream and then 20 miles downstream in a total time of 5 1/3 hr. Find the speed of the boat.
I know you have to use V= d/t, but what is the equation for time because you have to factor in that upstream the boat is slower and downstream the boat is faster? Answered by Penny Nom. 





A river crossing 
20070316 

From tara: A river has a constant current of 4 kilometers per hour. At what angle
to a boat dock should a motorboat, capable of maintaining a constant
speed of 20 kilometers per hour, be headed on order to reach a point
directly opposite the dock? If the river is 1/2 kilometer wide, how long
with it take to cross? Answered by Stephen La Rocque. 





Rate of a boat and a river 
20061209 

From Dale: If a boat goes downstream 72 miles in 3 hours and upstream 60 miles in 6 hour, the rate of the river and the rate of the boat in still water respectively are ____? Answered by Stephen La Rocque. 





Two problems 
20050429 

From Sara:
#1 A boat is traveling in a straight line across a river from point D, directly opposite town P, to a point Q, two thirds of the distance from town P to town R. Towns P and R are towns on the same side of the lake and are 18 miles apart. Line DQ passes through town S, which is 8 miles north of town R. Points P, Q, and R are collinear. What is the length of QS in Miles?
How many miles does the boat travel across the river?
#2 What is the area of a regular hexagon if the perimeter is 24cm?
Answered by Penny Nom. 





Crossing a river 
20040909 

From Barb: Nine men and two boys, trekking through the jungle, need to cross a river. They have a small inflatable boat and it's easy enough to row it across the river. The boat, however, can hold no more than one man or the two boys. How can they all get across? (Hint. suppose there was only one man and two boys) Does it make math sense and what would the answer be Answered by Penny Nom and Claude Tardif. 





Bob swam across a river 
20020522 

From Torri: Bob swam across a river 420 ft wide. A strong current carried him 580ft downstream as he swam. Find x, the distance bob actually swam. Answered by Penny Nom. 





Two ferry boats 
20010325 

From Gil: Two ferry boats leave from opposite shores. One is faster than the other. They meet 720 yards from the nearest shore. They proceed to destination and upon returning they meet 400 yards from the other shore. What is the exact width of the river. Answered by Penny Nom. 





Rowing on the Charles River. 
19970917 

From Fawwaz Muraisi: On the Charles River in Boston, the Harvard bridge and the Longfellow bridge are 1 mile apart. The MIT crew starts rowing upstream at the Longfellow bridge. As the crew passes under the Harvard bridge, the coxswain's hat falls into the river. Ten minutes later, the coxswain notices and turns the boat around instantaneously. He has t he crew row back to get it, rowing at the same constant rate. By the time the team reaches the hat, they are back at the Longfellow bridge.How fast is the river flowing? Answered by Harley Weston. 

