Math practice for 13 year olds - page 302 of 413
Number of problems found: 8254
- Waste - cutting metal
In the workshop, they cut 50 circles with a diameter of 9 cm from a rectangular sheet with dimensions of 50 cm and 100 cm. What percentage of the sheet was a waste? - Circle area increase
How does the area of a circle change if we double its radius? How many times does its area increase? - Diamond perimeter
Calculate the circumference of a diamond whose area is 288 cm square and one diagonal is 12.4 cm. - Four circles
1) Calculate the circle radius if its area is 400 cm² 2) Calculate the radius of the circle whose circumference is 400 cm. 3) Calculate circle circumference if its area is 400 cm² 4) Calculate the circle's area if the perimeter is 400 cm. - Prism volume
Calculate the volume and surface area of the body that is created by cutting out a three-sided prism of the same height from a cuboid with dimensions of 10 cm, 15 cm, and 20 cm, whose base is a right-angled triangle with dimensions of 3 cm, 4 cm, and 5 cm - Workers digging
The three workers will dig one big pit in two days. How many workers would dig seven large pits in three days? - Two workers
Two workers make 138 parts/items. The first one produces 30% more than the second. How many items will each produce? - Three numbers
The sum of the three numbers is 287. These numbers are in a ratio of 3:7:1/4. Find these numbers. - Wheel diameter
A 1 m diameter wheel rolled along a 100 m long track. How many times did it turn? - Quadrangular prism
The quadrilateral prism has a volume of 648 cm³. The trapezoid, which is its base, has the dimensions a = 10 cm, c = 5, and height v = 6 cm. What is the height of the prism? - Baker
The baker needs 10 kg of flour to make 12 kg of dough. How much flour does he need to make a 100 kg dough? - Earth's diameter
The Earth's diameter on the equator is approximately 12750 km. How long does the Gripen fly over the Earth above the equator at 10 km if it is at an average speed of 1500 km/h? - Square prism
Calculate the volume of a square prism with a height of 2 dm and a base that is a rectangle with sides of 17 cm and 1.3 dm. - Sea water
One tonne of seawater contains 25 kg of salt. How many tonnes of seawater needs to be evaporated to obtain 1 tonne of salt? - Flowerbed
The flowerbed has a length of 3500mm and a width of 1400mm. How much foil is needed to cover the flowerbed? How many m² of foil was consumed for its production (add 10% of the material to the joint and waste)? How many liters of air is inside the enclosur - Mr and Mrs
Mr. Calda and Mrs. Cald have a total of 139 years. How many years have when we known that Mr. Calda is nine years older than Mrs. Cald? - The tram
The tram is moving with acceleration a = 0.3 m/s2. How long will it pass the first meter of the track? How long does it take 10 meters? What is its speed at the end of the 10-meter track? - Two pumps filling
A pool with one pump fills in 14 hours and the other in 15 hours. How long will the pool fill when both pumps are used? - Driver
The driver of the supply car reckoned that at the average speed of 72 km/h arrived at the warehouse for 1 1/4 hours. After 30 km, however, he unintentionally drove to the gas station and had ten minutes delay. At what average speed would you have to go th - Trapezoid proof
Trapezoid ABCD with bases AB = a, CD = c has height v. The point S is the center of the arm BC. Prove that the area of the ASD triangle is equal to half the area of the ABCD trapezoid.
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