Maths practice for 12-year-olds - page 180 of 351
Number of problems found: 7018
- Planetarium dome area
The planetarium's dome is shaped like a hemisphere with a diameter of 17 m. Determine the size of the projection area - Three-sided prism
Find the area of the largest wall of a three-sided prism, with a height of 4 dm and an edge length of 5 cm and 6 cm. - Wheel teeth calculation
The white wheel has 24 teeth. The black wheel has fewer teeth than the white wheel. Both wheels return to their initial position for the first time after two revolutions of the white wheel. How many teeth does the black wheel have? - The convoy
During a military exercise, the convoy left the camp at 5 hours at a speed of 40 km/h. Half an hour later, the commander sent a motorcycle clutch at a speed of 70 km/h. How long before the motorcycle clutch reaches the column? - Tent air volume
The tent's floor consists of a square with a side of 2.4 m, and the front and back wall is an isosceles triangle with a height of 1.6 m. Calculate the volume of air in the tent in liters. (Laid triangular prism.) - The shadow
The shadow of a 1 m high pole thrown on a horizontal plane is 0.8 m long. At the same time, the shadow of a tree thrown on a horizontal plane is 6.4 m. Determine the height of the tree. - Quadrilateral pyramid
Calculate the volume of a regular quadrilateral pyramid, which has the size of the base edge a = 12 cm and a height of 11 cm. - Diameters of euro coins
When paying, we use euro coins with the following diameters: The 10-cent coin has a diameter of 19.75 mm. The 20-cent coin has a diameter of 22.25 mm. The 50-cent coin has a diameter of 24.25 mm. Find out in what ratio the diameters of these coins are. - Prism height calculation
Calculate the height of a regular quadrilateral prism whose base is a rhombus. The edge in the base is 7 cm long, the opposite edges are 5 cm apart, and we also know that the entire body has a volume of 1 dm³. - Length of the arc
What is the arc length of a circle k (S, r=68 mm), which belongs to a central angle of 78°? - School painting time
A four-member group planned to paint the school for ten days. After two days, one member fell ill. If they worked with the same effort, how many days were the school painted? - Diggers
The excavation was carried out in 4 days, and five workers worked on it for 7 hours daily. Determine how long it would take to excavate if seven workers worked on it 8 hours a day. - Dog food duration
Food for 42 dogs is enough for 35 days. After 15 days, the two dogs adopted new owners. For how many days will the food for the remaining dogs be enough? - Dividing nuts
How many nuts do you have when dividing them between 2, 3, 4, 5, 6, 8, and 10 children? (smallest possible number) - Fraction multiplication puzzle
The result of multiplying two fractions is 9 3/5. If one of the fractions is 9 3/7, find the other fraction. - Block side calculation
The block has the dimensions a = ?, b = 10 m, c = 6.2 m, the surface is 192.04 m². What is the length of side a? - Enclosure width calculation
The enclosure for lions in the ZOO has a rectangular shape with a length of 5.6 m and a width of 6.8 m. During the reconstruction, the length of the fence must be adjusted to 5.2 m so that the size (areas) of the paddock stays the same. What will be the w - Cutting the prism
A prism with a square base with an area of 1 cm² and a height of 3 cm was cut from a cube with an edge length of 3 cm. What is the body's surface formed from the cube after cutting the prism? - Tram stop
The blue tram stops every 12 minutes, and the red one stops for 8 minutes. At 8 o'clock, they left the stop together. How many times do they meet at a stop before 11 AM? - Interior angles
Calculate the interior angles of a triangle that are in the ratio 2:3:4.
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