Harmonic mean - practice problems - page 8 of 10
The harmonic mean is a type of average that is particularly useful for calculating rates, ratios, or situations involving reciprocals.It is calculated as the reciprocal of the arithmetic mean of the reciprocals of a set of numbers.
The harmonic mean is often used when dealing with averages of quantities like speed, where time and distance are inversely related. It tends to be less affected by extremely large values in a dataset, making it more appropriate for skewed distributions compared to the arithmetic mean.
A key property of the harmonic mean is that it is always less than or equal to the arithmetic mean and the geometric mean for any set of positive numbers.
It is commonly applied in finance, such as calculating the average price-to-earnings ratio, and in physics, such as finding equivalent resistance in parallel circuits. The harmonic mean is not suitable for datasets containing zero or negative values, as it is undefined in such cases.
Number of problems found: 186
- Independently 3874
Josef would do the work himself in 5 hours. Josef and Michal would do the work together in 3.5 hours. Determine how long it would take Michal to do the job independently. - Determine 3851
Michal would cut the fence himself in 12 hours. It would take Michal and Juraj 8 hours together. Determine how long it would take for Juraj to do the job. - 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?
- Harmonic and arithmetic means
The local Utah Department of Child Service office wants to project staffing needs based on current social worker assignments. They have the number of cases per social worker for the following staff: Mary: 25 John: 35 Ted: 15 Lisa: 45 Anna: 20 Calculate: a - 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, and the second pump fills the tank 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 had 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 p - Forth and back
The car drives from point A to point B at 78 km/h speed and back at 82 km/h. If I went there and back at a speed of 81 km/h, the 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? - 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 and the second tributary for 35 hours. Sometimes, both inlets open, then a second tributary closed, and they filled the tank in four hours. What time does water flow from both tributaries - Grass garden
Mr. Grass would mow the garden for 5 hours, and his son Michael could do it for 7 hours. They agreed to 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 work. Is he ri - 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 does the 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?
There are two diggers. One digger digs a pit 77 hours per second, digging 1.2 times faster. a) how long did digging a pit with a second digger take? b) how long did it take to dig together?Do you have homework that you need help solving? Ask a question, and we will try to solve it. Solving math problems.
