Maths practice for 12-year-olds - page 347 of 350

Number of problems found: 6988

Earth parallel
Earth's radius is 6377 km long. Calculate the length parallel to latitude 75°.
Tree trunk
Calculate the average tree trunk with a circumference of 192 cm.
Equilateral triangle
Calculate the side of an equilateral triangle if its area is 886 mm².
Circle
How big is the area of a circle if its circumference is 51.2 cm?
Truncated cone
Calculate the volume of a truncated cone with base radiuses r₁=19 cm, r₂ = 11 cm, and height v = 5 cm.
DIY press
Under the socialist regime, in some socialist countries, owning a typewriter required special permission. That has hindered the spread of DIY literature (manually transcribed through carbon copy paper for typewriters). Calculate how many typewriters today
Copper sheet
The copper plate has a length of 2.2 m, width 92 cm, and weighs 5.6 kg. What is the plate thickness if 1 m³ weighs 8732 kg?
Car range
Kia has an average diesel consumption of 5.2 liters per 100 kilometers. What is the range of the car for 138 euros if fuel costs 1.3 EUR/liter, if the tank has a volume of 64 liters?
Forest nursery
In the Forest nursery plant, one borovice to 2 m². Calculate how many plants are planted in the area of 510 acres.
Fuel consumption
Kia car has an average nafty consumption of 6.4 liters per 100 kilometers. What is the car range for a full tank of volume 71 liters?
Pipe
Steel pipe has a length of 1.7 meters. About how many decimetres is 1/3 less than 8/9 of this steel pipe?
Flags
How many different flags can be made from green, white, blue, red, orange, yellow, and purple materials, so each flag consists of three different colors?
Carbon dioxide
Calculate how many grams of oxygen are in 59 grams of carbon dioxide CO₂. The relative atomic mass of oxygen is 16, and of carbon is 12.
Iron
Iron ore contains 61% iron. How much iron ore is needed to produce 29 tons of iron?
Air mass
What is the weight of the air in a classroom with dimensions 10 m × 3 m × 3 m? The air density is 1.293 kg/m³.
Barrel of oil
The barrel of oil weighs 283 kg. When it molded 26% oil, it weighed 216 kg. What is the mass of the empty barrel?
Magnification of the square
If we increase the square side, increase the area of the 57 %. About what percentage was increased on its side?
Circle and angle
What is the length of the arc of a circle with radius r = 432 dm with central angle 0.53 rad?
Promile
Calculate the 17.6 ‰ of 353.
Slovakia banks
It is an unwritten rule that the larger bank in Slovakia (number of clients, balance sheet) has the worst / more expensive services offered to clients. Perhaps customs and herd customers prefer only the trio SLSP, VUB, and Tatrabanka. Calculate how many t

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