Harmonic mean - practice problems - page 5 of 9
Number of problems found: 171
- Two cities
The car goes from city A to city B at an average speed of 70 km/h and back at an average speed of 50 km/h. If it goes to B and back at an average speed of 60 km/h, the whole ride will take 8 minutes less. What is the distance between cities A and B? - Two pumps together
The first pump will fill the tank itself in 3 hours and the second one in 6 hours. How many hours will the tank be full if both pumps are worked simultaneously? - 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. - Three pumps
We are filling the pool. The pool would fill the first pump in 12 hours and the second in 15 hours. If all three pumps ran simultaneously, they would fill the pool for 4 hours. How long would the pool fill only with the third pump?
- The pool
The pool contains 220 m³ of water. Workers can empty the pool 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? - Express train
An international express train drove from Kosice to Teplice. In the first 279 km, the track was repaired; therefore, it was moving at a speed of 10km/h less than it was scheduled to drive. The rest of the 465 km trip has increased the speed by 8 km/h to t - Working together
One worker performs work in 3 days, the second in 5 days. How much do they work together? - 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? - Right isosceles triangle
The right isosceles triangle has an altitude x drawn from the right angle to the hypotenuse dividing it into two equal segments. The length of one segment is 5 cm. What is the area of the triangle?
- Minutes 7177
The tank holds 140 liters of water. The tank is filled with a tap in 5 minutes, and the drain is emptied in 7 minutes. How long will it take for the empty tank to fill if we open the faucet and drain? - Soldier
An experienced soldier digs a good trench in 30 hours. Two soldiers dug the same trench every 40 hours. How many hours will the ditch dig all three together? - Summer tires
Three tire servants must change the summer tires on six cars in 2 hours. Mark's replacement would take 4.5 hours, Jirka would do it in 3 hours and 10 minutes, and Honza in 4 hours. Will they be able to replace all tires at the desired time? - Evening shift
While working the evening shift, Officer K took 8 hours to complete a task at his workstation, and Officer M took 10 hours to complete the same task at his workstation. How many hours would it take Officer K and M to complete the same task, each working a - Together 3
If Sally can paint a house in 4 hours, and John can paint the same house in 6 hours, how long will it take for both of them to paint the house together?
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