# Water reservoir

The water reservoir is filled through one inlet 4 hours later than both together, then another inlet 9 hours later than both together. For how long is filled by each separately?

Result

a =  10 h
b =  15 h

#### Solution:

$\dfrac1a + \dfrac1b = \dfrac1s \ \\ s = \dfrac{ab}{a+b} \ \\ a = 4 +s \ \\ b = 9 + s \ \\ \ \\ a = 4 + \dfrac{ab}{a+b} \ \\ b = 9 + \dfrac{ab}{a+b} \ \\ \ \\ a^2 = 4(a+b) \ \\ b^2 = 9(a+b) \ \\ \ \\ a>0; b>0 \ \\ a = 10 \ \\ b = 15 \ \\ s = 6 \ \\$

Our examples were largely sent or created by pupils and students themselves. Therefore, we would be pleased if you could send us any errors you found, spelling mistakes, or rephasing the example. Thank you!

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

Be the first to comment!

Tips to related online calculators
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?
Do you want to convert time units like minutes to seconds?

## Next similar math problems:

1. Mixing water
The 30-liter container should we fill with water at 60 degrees Celsius. How many liters of water 80 degrees C hot and how many liters of water 20 degrees Celsius warm we have to mix?
2. The pool
The pool contains 220 m3 of water. The pool can be emptied either: a) 10 hours of pipe B and 8 hours of pipe A, or b) 10 hours of pipe A and 7 hours of pipe B. How many cubic meters of water will flow in 1 hour from pipe A and how many from pipe B?
3. Cork and swimming
If a person weighs 80 kg, how many kilograms of cork must take swimming belt to use it to float on water? The density of the human body is 1050kg/m3 and cork 300kg/m3. (Instructions: Let the human body and cork on a mixture that has a density of 1000kg/
4. Solution
What amount of 80% solution and what amount of water is needed to mix in order to obtain two liters of 60% solution of this mixture?
5. Two math problems
1) The sum of twice a number and -6 is nine more than the opposite of that number. Find the number. 2) A collection of 27 coins, all nickels, and dimes, is worth $2.10. How many of each coin are there? The dime, in United States usage, is a ten-cent coi 6. Beds At the summer camp, there are 41 chalets. Some rooms are 3-beds, some 4-beds. How many campers from 140 are living in 3-bed? 7. Home cleaning Mr. Smith is cleaning up a big mess at home. In the closet, he finds a solution that is 5% bleach, and another stronger solution that is 20% bleach. For this particular job, he needs 600mL of 15% bleach. How much of each type (to the nearest mL) should he 8. Tea mixture Of the two sort of tea at a price of 180 CZK/kg and 240 CZK/kg we make a mixture 12 kg that should be prepared at a price of 200 CZK / kg. How many kilos of each sort of tea will we need to be mixed? 9. Sales of products For 80 pieces of two quality products a total sales is 175 Eur. If the first quality product was sold for n EUR per piece (n natural number) and the second quality product after 2 EUR per piece. How many pieces of the first quality were sold? 10. Bonbons Create a mixture of 50 kg of candy on price 700Kč. Candies has prices: 820Kč, 660Kč and 580Kč. Use cross rule. 11. Sweets We want to prepare 5 kg of sweets for 150 CZK. We will mix cheaper candy: 1 kg for 120 CZK and more expensive candy: 1 kg per 240 CZK. How much of this two types of candy is necessary to prepare this mixture? 12. Alcohol mixture From 55% and 80% alcohol we have to produce 0.2 kg of 60% alcohol. How many of them do we use in solution? 13. CuZn Brass is an alloy of copper and zinc. The 10 centimeter brass cube has a weight of 8.6 kg. Copper density is 8930 kg/m3, the zinc density is 7130 kg/m3. Calculate how many kg of copper and zinc a cube contains. 14. Concentration How many grams of 65% and 50% acid is to be mixed to give 240 g acid with a concentration of 60%? 15. Ring The ring made from gold and copper alloy has a weight of 14.5 g and a volume of 1.03 cm3. How much gold and how much copper it contains? The metal densities are Au 19.3 g/cm³ and Cu 8.94 kg·dm-3 16. Mixing If we mix 5 kg of goods of one kind and 3 kg second one, resulting mixture cost 16.50 EUR/kg. If these quantities are mixed in reverse - first three kilograms and 5 kilograms second cost of mixture is 18.50 EUR/kg. What is the price of one kg of goods of 17. Banknotes$ 1390 was collected. How much was in $20 notes and how many in$50 notes in that order? How many solutions exists?