Maths practice for 12-year-olds - page 349 of 351

Number of problems found: 7018

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
Tesco Clubcard
František got quarterly billing vouchers for Tesco ClubCard, taking goods worth 6.5 Eur. Calculate the average monthly amount Tesco stores bought goods. Tesco ClubCard works for every Euro spent; you get one ClubCard point, which Tesco will convert to one
Human buying irrationality
I longer watch processors for Socket A on the secondhand market, Athlon XP 1.86GHz with a PR rating of 2500+ costs $7, and Athlon XP 2.16Ghz with a PR rating of 3000+ currently costs $16. Calculate: About what percentage of the Athlon XP 2.16Ghz is more p
Trapezium zoom
How many times should the area of the trapezoid be increased if all sides and altitudes increase 5 times?
Sumo competition
In the competition for the heaviest man was 5 competitors. The first three together weighed 369 kg. What is the minimal weight of the winner if a contestant weighed with an accuracy of one kilogram?
Triangle angles
The angles α, β, γ in triangle ABC are in the ratio 6:2:6. Calculate the size of angles.
Degrees to radians
Convert magnitude of the angle α = 538°38'17" to radians:
Window
Peter demolished a box hole in the wall for the window frame 147×51 cm. When they come, they will find a master-fitted frame and window that glass is 13.3 cm from the hole in each direction. Calculate how much percent less light enters the window th
Solidarity
Imagine a word solidarity means that salt donation to the needy, who have neither the salt. If we take the word solidarity, it is a word based on salt + gift (only in the Slovakian language). Calculate how many kilos of salt a sympathetic citizen "gives"
Density - simple example
Material of density of 1189 kg/m³ occupies a container volume of 64 cm³. What is its mass?
Circle arc
The circle segment has a circumference of 135.26 dm and 2096.58 dm² area. Calculate the radius of the circle and the size of the central angle.

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