Maths practice for 12-year-olds - page 335 of 362
Number of problems found: 7223
- Five tractors
Five tractors plow the field in 4.8 hours. How long would it take to plow this field if, after 1.5 hours of work, two tractors went to a different field? - Common cylinder
I've quite a common example of a rotary cylinder. Known: S1 = 1 m2, r = 0.1 m Calculate : v =? V =? Can you verify the results? - Wood
Wood contains 12% water. One m³ of wood weighs 650 kg. How many liters of water does it contain? - Cargo
The weight of the cargo car is 761 kg. The car's weight is 23% of the total weight of the car+cargo. What is the weight of the cargo load? - Container
On the first day, I removed 1/4 of the water from the full container, and on the second day, I removed 1/5 of the remaining water. Thus, how many percent remain container-filled? - Pumps
The first pump flows 16 liters per second into the basin by the second pump 75% of the first and by the third pump half more than the second. How long will it take to fill the basin with all three pumps simultaneously, a volume of 15 m³ (cubic meters)? - Family
Martin has just as brothers and sisters. But his sister Jana has two times more brothers than sisters. a) How many children are in this family? b) How many boys and how many girls are in the family?
- Percentage of waste
In a square plate with a side 75 cm, we cut four same circles. Calculate the percentage of waste. - Square and circle
Into the square is an inscribed circle with a diameter of 10 cm. What is the difference between a circumference square and a circle? - Minute-hand
How long will a large (minute) hand travel on the clock for 48 minutes if its length is 56 cm? - Again saw
We have a sculpture beam from the tree trunk with a rectangular cross-section with dimensions 91 mm and 87 mm. What is the trunk's smallest diameter? - Velocipede
The front wheel of the velocipede from the year 1880 had a diameter of 1.8 m. Suppose the front wheel is turned again once, then the rear wheel six times. What was the diameter of the rear wheel? - Plumber
The plumber had to cut the metal strip with dimensions of 380 cm and 60 cm to the largest squares to no waste. Calculate the length of the sides of a square. How many squares cut it? - Gardens
The garden has a square shape with a circumference of 124 m. Divide it into two rectangular gardens; one should have a circumference of 10 meters more than the second. What size will the gardens be? - Buses
Buses Ikarus and Karosa simultaneously started at 8:00 from the final station. Ikarus is returned to the station after 30 minutes. Karosa after 45 minutes. At what time do both buses again return to the station?
- Weight of air
What is the weight of air in the living room measuring width 8 m, length 5 m, and height 3.1 m? Air density is ρ = 1.2959 kg/m³. - Train from Prague
The first train from Prague started at 8:00 AM at 40 kilometers per hour. Train from Ostrava started at 9:20 at 80 km per hour. How many hours and how far from cities with trains meet if the distance of cities is 400 km. - Train from Brno The first train started from Brno at 8 AM at 60 km per hour. The second train started from Opava at 7 o'clock at 40 kilometers per hour. In how many hours and how far from cities do trains meet when the distance between cities is 200 kilometers?
- Street numbers
Lada came to his aunt. On the way, he noticed that the houses on the left side of the street had odd numbers on the right side and even numbers. There are five houses with an even number on the street where his aunt lives, which contains at least one digi - Parking
One hundred twenty vehicles are parked in the morning. Passenger car is charged 20 CZK and 50 CZK per bus. The guard collected for parking 2640 CZK in total. How many cars and buses stood in the parking?
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