Math practice for 13 year olds - page 72 of 428

Number of problems found: 8557

Small density cube
Calculate the mass of a cube with an edge of 15 cm made of oak wood with a density of ρ = 800 kg/m³.
Mobile price increase
The mobile was increased by a quarter of the original price and then again by a quarter of the new price. How much did the mobile cost if its final price was 125 euros?
Car consumption average
The car consumes up to 16 l in the city, but on a longer trip, the consumption drops to 10 l? 500 km per month in the city and 1650 km outside the city. What is the consumption of a car per 100 km?
Block volume ratio
The block surface is 5,632 m². The lengths of the edges are in the ratio 1: 2 : 3. Calculate the volume of the cuboid.
Square side increase
We increased the side of the square by 12% from the original 15cm. For a, what was the perimeter and area of the new square? By what percent did the perimeter and area increase?
Prism volume surface
Calculate a prism's volume and surface area with a base of a right triangle with cantilevers of length 40 and 43 cm. The height of the prism is 60 cm.
Block surface ratio
The volume of the block is 7,500 dm³. The lengths of the edges are in the ratio 3: 4: 5. Calculate the surface area of the cuboid.
Cuboid surface ratio
The volume of the cuboid is 960 cm³. The lengths of the edges are in the ratio 1 : 3: 5. Calculate the surface area of the cuboid.
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?
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
Karel went for a walk at a speed of 5 km/h. After 3 hours, Ondra rode to him with an important message. He was moving at a speed of 20 km/h. How many minutes did Ondra catch up with Karel?
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 6m?
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
The tin body transferred 150,000 J of heat, and its temperature dropped by 10°C. Calculate the mass of the tin body. (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 560m. 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?

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