Math practice for 13 year olds - page 73 of 414

Number of problems found: 8262

Ball box percentage
A ball with a diameter of 10 cm is in a cube-shaped box with an edge of 10 cm. What percentage of the box does the ball fill?
Paper grade distribution
There are 28 pupils in the class. Twenty-seven of them wrote the control paper in mathematics. Four students had a one, 8 had a two, 12 students had a three, and 3 had a four. Express this distribution as a percentage.
Horse oats consumption
Three horses will eat 36 kg of oats in two days. How many kilograms do 5 horses need for 4 days? Help yourself by adding or subtracting.
Karel Ondra pursuit
Carl went for a walk at a speed of 5 km/h. After 3 hours, Andrew rode after him with an important message at a speed of 20 km/h. How many minutes did it take Andrew to catch up with Carl?
Forester sapling planting
Foresters planted 2,440 saplings in three days. On the second day, they planted 20% more saplings than on the first day, and on the third day, 15% less than on the first day. How many saplings did the foresters plant each day?
Observatory's dome
In our city, they decided to reconstruct the observatory's dome and cover it with sheet metal. At least how many square meters of sheet metal will they need if the dome is in the shape of a hemisphere with a diameter of 6 m?
Cylinder radius grinding
The carpenter worked on a rotary cylinder with a base radius of 2.5 dm and a height of 2 dm. He reduced the radius by 1 cm by uniform grinding, and the height of the cylinder was preserved. Calculate the percentage by which the volume of the cylinder has
Kitchen carpenter delivery
On October 1, 2022, the customer ordered a custom-made kitchen from a carpentry company. Delivery time is 1 month. Four carpenters should work on the order in the workshop for 21 working days. Will they be able to deliver the kitchen on time if one of the
Tin body mass
A tin object transferred 150,000 J of heat, and its temperature dropped by 10 °C. Calculate the mass of the tin object. (c of tin is 0.227 kJ/kg. °C). Enter the resulting weight in grams and round it to two decimal places.
Iron key temperature
By how much °C will the temperature of an iron key weighing 0.004 t change if it receives 360,000 J of heat? ( c of iron is 450 J/kg.°C )
Steel heat capacity
Calculate the mass heat capacity of a steel body weighing 2 kg, which was heated from an initial temperature of 15 °C to 80 °C by supplying 60 kJ of heat.
Ropeway angle length
The ropeway climbs at an angle of 22°30'. Calculate its length if the height difference between the lower and upper station is 560 m. Sketch a picture
Ladder building height
A ladder leans against the building; its length is 7.5 meters. The bottom is 2 meters away from the building. At what height is it leaning against the wall?
Triangle height calculation
Hello, I have a problem calculating the height on side z in the general triangle XYZ, where z=4 cm, x=1.5 cm, and y=3.7 cm. It was assigned in 8th grade when discussing the Pythagorean theorem. Thank you.
Castle painting cans
The castle has a length of 4 m and a cross-section in the shape of a square whose side is 15 cm long. Eight such castles must be painted. One kilogram can is enough for 6 m² of coating. How many cans of paint should be bought?
Makarska riviera
The motor boat departs from Baška Voda at 19:15 and arrives in Makarska at an average speed of 30 km/h at 20:00. However, a group of tourists from Germany must be in Makarska a third of the time earlier. What should the average speed of the boat be?
Pump tank emptying
Three identical pumps empty the tank in 1.8 hours. How long will it take 5 pumps to empty this tank?
Vehicle speed ratio
The speeds of two motor vehicles are in the ratio 7:4. How many kilometers will the slower vehicle travel simultaneously, if the faster vehicle travels 52.5 km?
Worker road repair
Six workers repair 48 meters of municipal road in 2 days. How many days will 3 workers with the same output repair 60 meters of the road?
Copper cylinder cooling
A copper cylinder weighing 15 kg transferred 114.9 kJ of heat to the surroundings during cooling. By how many degrees Celsius did it cool down?

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