Harmonic mean - practice for 13 year olds - page 5 of 6
Number of problems found: 104
- 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? - 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? - 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 - Madams
During the spring cleaning, ladies were going to wash the windows. Mother takes to wash all the windows 5 hours, the grandmother takes 3 times longer, and Paula washes all windows in 2 hours. How many hours will you spend washing the windows of this "wome - Car
The car goes from point A to point B at speed 86 km/h and back 53 km/h. If it goes there and back at speed 67 km/h trip would take 10 minutes shorter. What is the distance between points A and B?
- Tanker
The first pump can empty an oil tanker in 4.9 hour. The second pump can empty a tanker in 8 hours. If the first pump started at 4:00 and the second 1.4 hour later, at what time will the tanker be empty? - Steamship
Between the two ports on the river is going steamship. The journey there and back takes 8:42. Downstream steamship traveling at 20 km/h, upstream 9 km/h. What is the distance between the ports? - Workers
Two workers would fulfill a certain task when working together for 5 days, the first if he worked himself done work in 13 days. How many days will the second worker do the whole job? - Reciprocal
What is the reciprocal of the sum of the reciprocals of 7 and 6? - Drinking water
A man drinks a keg of water in 36 days, and a woman drinks in 65 days. How many days do they consume a keg together?
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