Maths practice for 12-year-olds - page 353 of 356

Number of problems found: 7113

Seedcake
Seedcake costs 20 cents. How many minimum seedcakes must we buy that we can pay in cash, only whole euros?
Equilateral triangle
Calculate the side length of an equilateral triangle whose area is 886 mm².
Circle
What is the area of a circle whose 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?
Cylinder
Calculate the dimensions of a cylindrical container with a volume of 10 litres if its height equals its base diameter.
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 a forest nursery, one borovice is planted per 2 m². Calculate how many plants are planted on an area of 510 hectares.
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 if each flag consists of three stripes of different colours?
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 mass of the air in a classroom with dimensions 10 m × 3 m × 3 m? The density of air 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?
Copper plate
Copperplate length 9 m and width 56 cm weigh 48.38 kg. What is the plate thickness if 1 m³ of copper weighs about 8700 kg?
Magnification of the square
If the side of a square is increased, the area increases by 57%. By what percentage was the side increased?
Circle and angle
What is the arc length of a circle with radius r = 432 dm corresponding to a central angle of 0.53 rad?
Promile
Calculate the 17.6 ‰ of 353.

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