Themes, topics - problems
- Rocket start
The body launched vertically up returns to the start site in 6 seconds. What height did it have?
- The work
The work was to be done by 150 workers. At the beginning of their work, their number reduced by 40, which increased the time of work by 5 and 1/3 of the schedule. How long did work take?
- Three people
Three people start doing a work at a same time. The first worked only 2 hours. The second ended 3 hours before the end. On an individual basis, it would take the first time to do the work 10 hours, second 12 hours and 15 hours third. How many hours did it.
- Athletic competition
In a 400 meter athletic competition, a participant covers the distance as given below. find the average speed? first 80 meters 10 m/s next 240 meters 7.5 m/s last 80 meters 10 m/s
- Luggage and air travel
Two friends traveling by plane had a total of 35 kg of luggage. They paid one 72 CZK and second 108 CZK for being overweight. If only one paid for all the bags, it would cost 300 CZK. What weight of baggage did each of them have, how many kilograms of lugg
Fifteen lumberjacks would take 12 days to destroy the broken trees. How many days would this work require if 5 workers added to it after 4 days?
- Calories 2
Ben eats approximately 2400 calories per day. His wife Sarah eats 5/8 as much. How many calories does Sarah eat per day?
- Ten cashiers
Ten cashiers are open at Tesco. Customers wait an average of 15 minutes. How many other cashiers have to open to reduce the waiting time by 4 minutes?
- Inlet minus outlet
Water flows into the tank through two pipes and flows out of the third pipe spontaneously. The pipe A itself would fill the tank in 3 hours, the pipe B itself would fille in 4 hours, and the pipe C itself would flow out in 12 hours. How long will the tank.
In the 19th century, bicycles did not have a chain drive, and the pedals were connected directly to the wheel axis. This wheel diameter gradually increased until the so-called high bicycles (velocipedes) with a front wheel diameter of up to 1.5 meters, whi
Ondra digs the bed in 20 minutes. Cuba in 30 minutes. For how long do they dig together?
- Five mechanics
Five mechanics will make a car for some time. How many cars can 30 mechanics produce at the same time?
- Constant motion
The car has undergone constant motion 120 km in 1 hour 30 minutes. Determine its average speed. Determine how long car drove in the first 20 minutes and 50 minutes from the start of the move.
After the floods, four equally powerful pumps exhausted water from the flooded cellar in 6 hours. How many hours would take a drained out with three equally powerful pumps?
A woman works at a law firm in city A which is about 50 miles from city B. She must go to the law library in city B to get a document. Find how long it takes her to drive round-trip if she averages 40 mph.
- Wave parameters
Calculate the speed of a wave if the frequency is 336 Hz and the wavelength is 10 m.
- The painter
In order for the painter to get the desired color, he must mix green and yellow in a ratio of 4: 7. If it has 28 l of green color, how many liters of yellow color should he add? How many liters of mixed color does he get?
- Construction of road
For the construction of the road dam, it is supposed to transport six trucks a total of 18 days. After three days, two more cars were sent to the construction site. How long will it take to carry the material?
- Hectoliters of water
The pool has a total of 126 hectoliters of water. The first pump draws 2.1 liters of water per second. A second pump pumps 3.5 liters of water per second. How long will it take both pumps to drain four-fifths of the water at the same time?
Mushrooms lose 90% by weight drying. How many fresh mushrooms are needed for 5 kg of dried mushrooms?