Themes, topics - math problems
Number of problems found: 1081
- The bath
Dad poured 50 liters of water at 60°C into the tub. How much cold water must be added at 10°C to obtain a bath that has a temperature of 40°C?
Kuba makes a deal with a shepherd to take care of his sheep. Shepherd said Kuba that after a year of service, he would receive twenty gold coins and one sheep. But Kuba resigned just after the seventh month of service. But shepherd rewarded him and paid h
- Weighted harmonic average
Ten workers will do some work in 2 minutes, five workers in 10 minutes and three workers in 6 minutes. How many minutes per average worker per worker?
- All pairs
Determine all pairs (m, n) of natural numbers for which is true: m s (n) = n s (m) = 70, where s (a) denotes the digit sum of the natural number a.
- Current in the conductor
Calculate the current in the conductor (in mA) if it is connected to a 4.5 V voltage source and its resistance is 20 (ohm).
- The bulb
What is the resistance of a filament lamp when it is connected to a 9V battery and has a current of 120 mA?
- An airplane
An airplane flies 1440 km in 2 1/4 hours. What is its average speed in km per hour?
- RC time constant
You introduced 1 Coulomb worth of electrons into the inner volume of a dielectric material with ϵr=6. Thirty minutes later, you found that only 36.79% of the electrons were in the internal volume. Determine the conductivity σ of the dielectric material.
- Dance ensembles
4 dance ensembles were dancing at the festival. None had less than 10 and more than 20 members. All dancers from some of the two ensembles were represented in each dance. First, 31 participants were on the stage, then 32, 34, 35, 37, and 38. How many danc
How much m ^ 3 of sand can be loaded on a car with a load capacity of 5 t? The sand density is 1600 kg/m3 .
We're going to Grandma. We still have 24 km left. How far does Grandma live if we have traveled from the total distance: half, a third, a fifth?
Three buses follow the same circular route. The first driver is the slowest because he has many stops, and it takes him 90 minutes to cross the route. The second driver will pass the circuit in 1 hour. The third driver has the fewest stops, and the circui
- Up and down motion
We throw the body from a height h = 5 m above the Earth vertically upwards v0 = 10 m/s. How long before we have to let the second body fall freely from the same height to hit the Earth at the same time?
- Nautical miles
How many nautical miles do they sail if the route is shown on a 1:25 000 scale map with a 7.4 cm long line?
- Two xeroxes
The performances of the two copiers are in the ratio 3: 4. A machine with higher power will make 7,200 copies in one hour. How many copies will both machines make together in 5 hours?
By what percentage does the sound intensity increase if the sound intensity level increases by 1 dB?
- Six painters
Six painters paint an area of 120 m2 in 4 hours. How long does it take for 12 painters to paint 480 m2 with the same performance?
- Ice floe
What is the volume of an ice floe weighing 326 kg? The density of ice is only 920 kg/m3.
- Book reading
Susan thought, "If I read 15 pages a day, I will read the whole book in 8 days. “How many pages would she have to read a day if she wanted to finish the book on the 6th day from the start of reading? And how many pages does the book have?
- Mr. Ben
Mr. Ben drives bricks to the construction site. If he drove three times a day, he would make bricks in 8 days. How many times a day would he go every day to be done 2 days earlier?