Harmonic mean - practice problems - page 8 of 9
Number of problems found: 171
- Grass garden
Mr. Grass would itself be mowed garden for 5 hours. His son Michael could do it for 7 hours. They agreed that they wake up at 5 am and begin to mow together. Ms. Grass needs to drive into town at 8.30. Michael says that at that time, they're done with wor - Two workers
Two workers work together and perform the job in 12 hours. If one has done half the work and then the second worker next half of the work, it will take 25 hours. How long would it take to job them separately? - 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. - Painters
The first team of painters would paint the bridge in 15 days, the second in 10 days. After three days of working together, the second team goes out and continues only with the first team. How many days took the second team to finish painting the bridge?
- 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? - Garden
Father dug up the garden in 11 few hours. Son in 15 hours. How many hours does it take to dig up the garden together? - Fire tank
The whole fire tank was discharged once in 5 days by first out by a second in $n day. Once firefighters pumped out 6/13 of water out from the tank and then let the water flow out both drains. How long does it take empty the tank? - 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?
- Three workers
Three workers, A, B, and C, have to work on a specific task. Workers A and B completed the task in 12 days, B with C for 19 days, and A with C for 24 days. How long would it take to complete the task for everyone alone? How long would it take to complete - Blueberries
Marie earns 3 liters of blueberries for 3.4 hours, and Peter 2.4 liters for 2.9 hours. How long do they pick one liter together? - Machines
In the workshop are three machines. The first is treated 250 parts for 4.7 hours, the second is treated 300 parts for 1.9 hours, and the third is treated 230 parts for 4.6 hours. How long will it take to make 3100 parts if all three machines are worked si - Two valves
Water fills the pool with two valves for 11 days. After 7 days, the workers stopped the first and second valve fill pool for 7 days. How many days took to fill the pool of each of the valves individually? - See harmonics
Is it true that the size of the central segment of any trapezoid is the harmonic mean size of its bases? Prove it. The central segment crosses the intersection of the diagonals and is parallel to the bases.
- Average
What is the average speed of the car, where half of the distance covered passed at a speed of 64 km/h and the other half at 82 km/h? - Parquet floor
Three workers laid the parquet floor for 2.301 hour. The first would do this work alone 7 hours, the second in 6 hours. For how many hours would fulfill this work for the third worker if he worked alone? - Inflow - outflow
The tank will fill by inflow for 56 minutes and empties by outflow for 77 minutes. How long does it take to fill the tank if it is also opened to the inflow and outflow? - Painters
The first painter painted the fence himself for 4 hours, the second painter 1.2 hours sooner than the first, and the third painter slowest up to 16 hours. How long took them to paint the fence if they worked together? - Workers
Two workers, A and B, will be done work together for 15 days. They worked together for 13.5 days. Then A worker became ill, and worker B finished the job alone for 7.5 days. If every worker was working alone, how many days took the whole work for workers
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