Water current speed.

Two cities along the river are 100 km apart. The powerboat downstream runs for 4 hours, upstream for 10 hours. Determines the river's current speed.

Result

v =  7.5 km/h

Solution:

100 = 4*(a+v)
100 = 10*(a-v)

4a+4v = 100
10a-10v = 100

a = 352 = 17.5
v = 152 = 7.5

Calculated by our linear equations calculator.

Leave us a comment of example and its solution (i.e. if it is still somewhat unclear...):

Be the first to comment!

To solve this example are needed these knowledge from mathematics:

Looking for help with calculating harmonic mean? Looking for a statistical calculator? Do you have a system of equations and looking for calculator system of linear equations? Do you want to convert length units?

Next similar examples:

1. Walkers
From points A and B simultaneously started against each other two walkers. After meeting both continue to B. Second walker came to B 2 hours before the first walker. It's speed is 2.7 times of speed of the first pedestrian. How many hours went pedestria
2. Two planes
Two planes flying from airports A and B, 420 km distant against each other. Plane from A took off 15 minutes later and flies at an average speed of 40 km/h higher than the plane from B. Determine the average speed of this two aircraft if you know that it
3. Aircraft nose down
How long will fall airliner from a height of 10000 m at speed 1,000 km/h?
4. Blackjack TU160
Bomber Tupolev TU160 started at 9:00 from the airport and flew at average speed of 1850 km/h toward the airfield B distant 3500 km. After evaluating the danger from the airport B started at 9:45 B towards A fighter MIG 29 at an average speed 2300 km/h. At
5. Aircrafts
Above the town hall tower flew the plane with constant speed 592 km/h and 15 minutes later the second plane at speed of 675 km/h. How long and how far from the town hall will be aircrafts caught up?
6. Athletic competition
In a 400 meter athletic competition, a participant covers the distance as given below. find the average speed? first 80 meters 10 m/s next 240 meters 7.5 m/s last 80 meters 10 m/s
7. Truck PRG-BA
Truck driving on highway from Prague to Bratislava at average speed of 72 km/h. At the moment when the truck passes 54 kilometer from Prague passenger car departs from Prague which travel to Bratislava at speed 90 km/h. When and where (at waht highway ki
8. Skier
At this point, the first skier lead 20 km before the second skier and travels at a constant speed 19 km/h. The second skier rides at 24 km/h. How long take him to catch up the first?
9. Wavelength
Calculate the wavelength of the tone frequency 11 kHz if the sound travels at speeds of 343 m/s.
10. Car and motorcyclist
A car and a motorcyclist rode against each other from a distance of 190 km. The car drove 10km/h higher than the motorcyclist and started half an hour later. It met a motorcyclist in an hour and thirty minutes. Determine their speeds.
11. Cyclist vs car
Cyclist rode out of the city at 18 km/h. 1 hour 30 minutes behind him started car and caught up with the cyclist in 50 minutes. How fast was driving the car? Where (what kilometer) from the city car overtook a cyclist?
12. Theorem prove
We want to prove the sentense: If the natural number n is divisible by six, then n is divisible by three. From what assumption we started?
13. Linsys2
Solve two equations with two unknowns: 400x+120y=147.2 350x+200y=144
14. Pooja
Pooja and Deepa age is 4:5, 4 years back it was 8:11. What is the age of Pooja now?
15. Lee is
Lee is 8 years more than twice Park's age, 4 years ago, Lee was three times as old. How old was Lee 4 years ago?
16. Family
Family has 4 children. Ondra is 3 years older than Matthew and Karlos 5 years older than the youngest Jane. We know that they are together 30 years and 3 years ago they were together 19 years. Determine how old the children are.
17. Father 7
Father is 6 times older than his son. After 4 years, the father will only be 4 times older. What are their present ages?