Harmonic mean - practice for 13 year olds - page 4 of 6
Number of problems found: 104
- 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. - 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 - Mow the lawn
Dano would mow the lawn in 12 hours and Milada in 16 hours. How long will it take the lawn mow together? - Pond
Workers will empty a pond with two open floodgates in 20 days. A larger floodgate will empty the whole pond in 30 days. For how long would he be emptied with a smaller floodgate?
- 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? - Pumps 4912
A pool with one pump fills in 14 hours and the other in 15 hours. How long will the pool fill when both pumps are used? - 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? - 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? - Together 3781
Milos would do the work himself in 5 hours. How much would it take Dan to do the job together in two hours?
- Cleaners
Milan would clean up the room for 2.5 hours, and Eric would take 10 hours. How long do they sweep the room together? - Together 3491
One painter would paint the school in 15 days. Together with the second painter, they painted the school in 6 days. In how many days the second painter would have painted the school himself? - Working together
One painter painted the nursery in 10 days, the second in 8 days. How many days will the nursery be painted if they work together? - Timber log
The ship goes from point x to y. Downstream it takes 4 hours, and upstream 6 hours. How long does it take from a point x to y a log? - Two pumps
The first pump fills the tank in 24 hours second pump in another 40 hours. How long will it take to fill the tank if it operates both pumps simultaneously?
- Three drivers
Three drivers driving in the same direction found that they have the same amount of gasoline. The first is enough to go 6 km, 4 km, second and third 3km. Gasoline they divided, so all three just drove to the nearest petrol station. How many km away was a - Tributaries
The first tributary fills the pool with water in 15 hours. The second tributary fills the pool in 10 hours. For how many hours is the pool filled with both tributaries? - Boots
Master shoemaker has three apprentices. First, do one pair of boots for two days, second for one day, and third for 1.5 days. How long would it take to make a couple of boots if they worked together? - Simultaneously 2570
Two cyclists will set off simultaneously from one place on the circular cycling track. How long before they meet? Do you know that Karel will drive in 6 minutes and Laco in 10 minutes? - The dam
The water reservoir is filled with the first tributary for 25 hours second tributary for 35 hours. Some time was, both inlets open, then a second tributary closed, and they filled the tank in four hours. What time does water flow from both tributaries? (E
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Looking for calculator of harmonic mean? Harmonic mean - practice problems. Maths practice for 13 year olds.