Harmonic mean - practice problems - page 2 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
- Excavators 82208
Two excavators dig a pit in 12 days. How much shorter will this job take if 8 excavators dig the hole? In 3 or 9 days? - Distribute 82137
We have a profit of 40000e, and the work took 30 days. The first worker is promised 38% of the profit but only works for 15 days, the second worker is promised 33% of the profit and works for 20 days, and the third is promised 28% of the profit and works - Throughout 82075
In the metro, trains run in one direction at the same speed and the same intervals. Yesterday, there were 24 trains throughout the day. More trains will run today, as the time interval between trains will be shorter by 20%. How many more trains will there - Together sewing
Eva sews a costume in 6 hours, Ivana in 8 hours, and Monika in 4 hours. How long will it take them to make the costume if they work together?
- Basement 81681
After the flood, the Nováks would pump water out of the basement with one pump in 120 minutes, the second in 300 minutes, and the third in 600 minutes. How many minutes will it take them to pump the water out of the basement if they use all the pumps at o - Apartment 81654
A woman cleans an apartment in 8 hours and a man in 10 hours. How many hours will they clean together? - Simultaneously 81441 The tank is filled through three openings, A, B, and C. The simultaneously open inlets A and B are filled in 1 hour, inlets A and C in 45 minutes, and inlets B and C in 1.5 hours. How long would it take to fill each inlet separately?
- Together 81046
Two painters are painting the factory fence together. If everyone worked alone, the first would finish the job in 16 days, the second in 20 days. When will they finish the work together? - Mountain climbing
Ken and his brother decided to go on mountain climbing 8 miles from their house to Mt. Daraitan at a rate of x mph (miles per hour). For the return trip, it was 2 mph faster. It took them 6 hours for the entire round trip. What is the x?
- Two painters
Two painters are assigned to finish painting the houses in a housing project. John can finish a house in 4 days, and Kurt painted it in 3 days. How long would it have taken if John and Kurt had worked painting the house together? - A person
A person buys 10 kg of commodity A at a rate of 2 kg per dollar, 20 kg of commodity b at a rate of 5 kilograms per dollar, and 30 kg of commodity C at a rate of 10 kg per dollar. Find the average price of kg per dollar. - Construction 71794
Two different trucks together would bring the construction material in 6 hours. However, after 4 hours, the first car was transferred to another job, and the second one was driven for another 6 hours. How many hours would it take for the first car to deli - Apartment 71114
A father and son paint the apartment together in 6 hours. My father would paint the apartment in 9 hours. In how many hours would the son paint the apartment himself? - Restaurant 65394
The restaurant was fully booked at lunchtime. While only three waiters staffed the restaurant, guests waited an average of 45 minutes for the lunch menu. On average, how many minutes will the guests wait if the three waiters are joined by two more waiters
- Together 65074
Jana washes 20 windows alone in 4 hours. Petra would be able to do it in 6 hours. How long will it take to work together? - Developed 64664
In the first stage, the cyclist covered 70 km at a speed of 22.1 km/h. In the second stage, he covered 40 km (a total of 110 km), and his average speed increased to 22.9 km/h. What an average speed he developed in the second stage! - Pentagon
The signboard has the shape of a pentagon ABCDE, in which line BC is perpendicular to line AB, and EA is perpendicular to line AB. Point P is the heel of the vertical starting from point D on line AB. | AP | = | PB |, | BC | = | EA | = 6dm, | PD | = 8.4dm - A frequency
A frequency table of grades has five classes (A, B, C, D, F) with frequencies of 2,14,13,8, and 1, respectively. Using percentages, what are the relative frequencies of the five classes? - Blueberries 48771
Mirka picks up a bucket of blueberries in two hours. Lorenzo fills one-third of the bucket every hour. How long would it take to fill one bucket together to the brim?
Two assemblers with the same daily output were to complete the assembly in 12 days. After 4 days, one of them got sick, and the other finished the assembly in another 16 days. How long would it take everyone to do the assembly by themselves?Do you have homework that you need help solving? Ask a question, and we will try to solve it. Solving math problems.
