Harmonic mean - practice for 14 year olds - page 4 of 5
Number of problems found: 98
- 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? - Average 4458
The first third of the track was driven by a car at a speed of 15 km/h, the second third at a speed of 30 km/h, and the last third at a speed of 90 km/h. Find the average speed of the car. - 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? - Work together
Michal and Dorota would do the work together in 2.25 hours. If Dorota had to do it herself, it would have taken her 6 hours longer than Michal. Determine when Dorota would do the work herself and that Michal would do it himself.
- 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 - Forth and back
Car drive from point A to point B at a speed of 78 km/h and back at 82 km/h. If I went there and back at a speed of 81 km/h journey would take five minutes less. What is the distance between points A and B? - 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? - 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 - Annual income
The annual income (in thousands of $) of fifteen families is 60, 80, 90, 96, 120, 150, 200, 360, 480, 520, 1060, 1200, 1450, 2500, 7200. Calculate the harmonic and geometric mean. - Two diggers
There are two diggers. One digger digs a pit 77 hours second, digging 1.2 times faster. a) how long took to dig a pit second digger b) how long took it to dig together - Pedestrian up-down hill
Pedestrian goes for a walk first at the plane at 4 km/h, then uphill at 3 km/h. Then it is in the middle of the route, turns back, and goes downhill at 6 km/h. The total walk was 6 hours. How many kilometers went pedestrians? - Painter Pavel
Painter Pavel painted the fence for 16 hours, and painter Petr the same fence painted for 13 h. How long should it take to paint the fence together?
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