Equation + harmonic mean - practice problems - page 3 of 5
Number of problems found: 89
- Half-filled 7336
The water tank is filled with the first inflow in one hour and 10 minutes and the second in 60 minutes. How many minutes will the tank be half-filled with both inlets if the second outlet is opened 12 minutes later? - Calculation 7334
In a computer center, one computer would work 12 hours to solve a task, and another, more powerful, would solve the same task for 10.5 hours. If both computers work together, the calculation time would be reduced for a certain period. Calculate how long i - The factory
The factory z can complete an order in 12 days, factory p in 18 days. How many days does an order completed when the first two days work only the factory z and then both factories? - Water reservoir
One drain hole emptied the water from the tank for 20 hours, with the second drain for 30 hours. How long will the water drain from this tank if we open two drains simultaneously?
- Harvesters
The first harvester will harvest the grain from the field in 20 hours, and the second, the more powerful in 10 hours. How long will it take to harvest this field by both harvesters if the second harvester has to be set up first, which takes 2 hours? The f - A report
Maricris can type a committee report in 5 hours. Jane helped Maricris, and together they finished the report in 3 hours. How long would it take Jane to complete the report she had worked on alone? - Two pumps
Pump A takes twice as long to fill a tank as B. Together, they take 2 hours to fill the tank. How long does each one take to fill the tank by itself? - Three pumps
The water tank is emptied with the first pump in 6 hours, with the second pump in 2 hours. In order to be emptied in 1 hour, all three pumps had to be started at once. How long will it take to empty the tank by only the third pump? - Flying
The airplane from Prague to Bratislava was flying at a speed of 60 km/h less and back by 70 km/h greater than the original speed. What was the original speed if the plane returned to Prague according to the timetable?
- Two brothers
Two brothers want to collect 20 kg of chestnuts. If only Marek collected, he would make it in 30 minutes. It would take Milan 10 minutes longer. How long after Mark does Milan have to start collecting to be finished in 18 minutes? - Turners
Two turners perform joint work in 3 hours. The first-turner would perform the job himself in 7 hours. How long would the same job last for a second-turner if he worked alone? - In and out
The empty tank is filled in 12 minutes and empty in 16 minutes. How long does it take to fill if we forget to close the drain? The tank has 1000 liters of volume. - The pool
The pool has a volume of 40 m3, and the water temperature is 20 °C. How much water at 100 °C should we pour into the pool to increase the water temperature by 5 °C? - ICE train
German runways test a new ICE train between Munich and Berlin. The train runs to Berlin at a slow speed of 100 km/h. Back from Berlin goes faster. How quickly did the train have to go on a return trip so that the average train speed for both journeys woul
- Oil tank and pipes
Two oil pipelines can fill the underground oil tank. The first is filled in 72 hours, and the second in 48 hours. How many hours from when the first pipeline began to fill the oil is necessary to start filling it with the second to fill in 1 and 1/2 days? - Two rooms
A woman cleans the room in 30 minutes, and a man in 90 minutes. How long will it take them clean two rooms? - Kilometers 4604
The tourist traveled 78 km in three hours. For part of the journey, he traveled by bus at an average speed of 30 km/h, and for the rest, he walked at an average speed of 6 km/h. How long did he walk, and how many kilometers did he walk? - Together 4511
One tractor would sow the field in 3 hours and the other in 7 hours. How long before the fields grow together? - Completes 4234
The worker completes the work in 12 days, the second in 10 days. The first worker kicks himself for four days, then the second worker comes. How long will it take to dig?
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