# The cruise ship

The cruise ship has a speed of 12 km / h at a calm surface. When we sail 45 km along the river and 45 km back, it took us exactly 8 hours. Which (constant) speed of flow of the river?

Result

v =  3 km/h

#### Solution:

Checkout calculation with our calculator of quadratic equations.

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 roots of a quadratic equation? Do you have a linear equation or system of equations and looking for its solution? Or do you have quadratic equation?

## Next similar examples:

1. Tourist Jirka
Distance between the points A and B is 13.5 km. Jirka went from point A to point B unknown speed and for an unknown period of time. Back to the point A went slower by 3 km/h which means that went 20 minutes more. How long Jirka took the return journey?
2. Wind drift
The plane flies at 860 km/h, passing distance 3000 kilometers with the wind and once again against the wind for 6 h 59 min. What is the wind speed?
3. 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
4. Speed of car
The car went to a city that was 240 km away. If his speed increased by 8 km/h, it would reach the finish one hour earlier. Determine its original speed.
Find the roots of the quadratic equation: 3x2-4x + (-4) = 0.
6. Evaluation of expressions
If a2-3a+1=0, find (i)a2+1/a2 (ii) a3+1/a3
7. 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?
8. Discriminant
Determine the discriminant of the equation: ?
9. Roots
Determine the quadratic equation absolute coefficient q, that the equation has a real double root and the root x calculate: ?
10. Equation
Equation ? has one root x1 = 8. Determine the coefficient b and the second root x2.
11. Square root 2
If the square root of 3m2 +22 and -x = 0, and x=7, what is m?
12. Solve equation
solve equation: ?
13. Variation equation
Solve combinatorics equation: V(2, x+8)=72
14. Equation with abs value
How many solutions has the equation ? in the real numbers?
15. Crystal water
The chemist wanted to check the content of water of crystallization of chromic potassium alum K2SO4 * Cr2 (SO4) 3 * 24 H2O, which was a long time in the laboratory. From 96.8 g of K2SO4 * Cr2 (SO4) 3 * 24 H2O prepared 979 cm3 solution of base. S
16. Expression with powers
If x-1/x=5, find the value of x4+1/x4
17. 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?