Math practice for 13 year olds - page 432 of 436
Number of problems found: 8718
- 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. - Isosceles right triangle
Calculate the area of an isosceles right triangle whose perimeter is 810 cm. - 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? - Concrete pipe
A concrete pipe is cylindrical with an inner diameter of 60 cm and an outer diameter of 67 cm. If it is 10 m long, calculate its total surface area. - Magnification of the square
If the side of a square is increased, the area increases by 57%. By what percentage was the side increased? - The cyclist
A cyclist travelled from a village to a town. The first half of the journey was at 24 km/h. The second half, which was mostly downhill, was at 38 km/h. The entire journey took 94 minutes. Calculate the distance from the village to the town. - 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? - Widescreen monitor
Widescreen monitors and televisions have flooded the market. Calculate the screen area of an LCD monitor with a diagonal of 27 inches at a 4:3 aspect ratio and then at a 16:9 aspect ratio. Is buying a widescreen monitor with the same diagonal more advanta - Cylinder - basics
A cylinder has a base radius r = 24 cm and height h = 62 cm. Calculate: a) The area of the base - Cylinder - A&V A cylinder has a volume of 463. Its base has a radius of 4. What is the total surface area of the cylinder?
- Similarity n-gon
6-gones ABCDEF and A'B'C'D'E'F' are similar. The area of 6-gon ABCDEF is S1=248 m², and the diagonal length FA is 28 m. Calculate the area of the 6-gon A'B'C'D'E'F' if F'A' = 36 m. - Glass mosaic
How many dm² of glass is needed to produce 97 panes in the shape of a regular hexagon with a side length of 21 cm? Assume that 10% of the glass is wasted in cutting. - Rectangle - sides ratio
Calculate the area of a rectangle whose sides are in the ratio 2:16 and whose perimeter is 1289. - Railways - golden parachutes
This is an example more from political science, or even a fairy tale about carp who won't drain their pond. Let's look at the short work of the director of the Carp Railway Company: 18 months of quasi "work" as director reduction and elimination - Electronics: Resistors in parallel
Concerning calculating the resistance of the parallel combination of resistors: (1)/(R) = (1)/(R1) + (1)/(R2) Calculate the R, if R1 = 17Ω a R2 = 20Ω - Barrel with liquid
Barrel with obilím weight 123 kg. When it sheds 56% of obilia, ha weight 74 kg, what is the weight of an empty barrel? - Triangle angles
The angles α, β, and γ of triangle ABC are in the ratio 6:2:6. Calculate the size of each angle. - Tractors
Two tractors with different capacities are to plough a field. The first tractor can plough the entire field in 14 hours. The second tractor can plough the entire field 8 hours déle. How long does it take both tractors to plough the entire field working to - Bits, bytes
Calculate how many different numbers can be encoded in a 64-bit binary word.
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