Maths practice for 12-year-olds - page 64 of 349
Number of problems found: 6972
- Resulting cross
From the corners of the square with a side length of 10 cm, we cut out small squares with a side length of 3 cm. What is the area of the resulting cross?
- Diamond-shaped 81516
How many diamond-shaped tiles with a side of 25 cm and a height of 20 cm are needed to pave a rectangular courtyard with sides of 30 m and 28 m if the joints represent 1/20 of the area?
- Decorations - spherical
The glass Christmas decorations have the shape of a ball with a diameter of 8 cm. In a small family business, they produce 50,000 pieces a year. The entire surface of these balls is covered with glitter. 400 g of glitter is needed to cover an area of 1 m²
- Body's 81509
What was the body's mass when it moved along a path of 70 dm and did 1.4 kJ of work?
- Resistance 81503
What is the value of the resistance of the rectifier diode in the forward direction if the current IF = 5 A flows through it and the voltage between the anode UF = 820 mV?
- Satellite 81495
The satellite flies at a speed of 8 km/s. Will it fly down the runway in two seconds?
- Threefold 81491
Find a number whose fivefold is 8 greater than threefold.
- Indistinguishable 81481
How many ways can a tower of five yellow and four blue cubes be built so that each yellow cube is adjacent to at least one other yellow cube? Yellow dice are indistinguishable, and so are blue dice.
- Fifteenths 81479
Little Aja planned to read the book, which has 120 pages, for 4 days. On the first day, she read a quarter of the whole book; on the second day, she had training and therefore only read two-fifteenths of the book; on the third day, she read seven-twentiet
- Calculate 81406
Calculate the equation and do the test. (x+6)/2 - (x+4)/4 = (2x+1)/3 – (x-4)/6
- Simultaneously 81403
Cars left two places 520 km apart simultaneously at speeds of 30 km/h and 50 km/h. Where and when will they meet?
- Calculation 81401
A regular four-sided pyramid has a volume of 2,160 liters and a base edge length of 12 dm. Calculate the height of the needle (sketch, calculation, answer).
- Perimeters 81399
Two squares are given. The first has a side length of 5 cm, the second 10 cm. Write the ratio of: for a- of their sides for b- their perimeters for c- their areas
- Notebooks 81398
Petr paid CZK 288 for 12 new notebooks. How much would he pay for 15 identical notebooks?
- If we want
A children’s pool has the shape of a cylinder with a base diameter of 4 m and a depth of 50 cm (sketch, calculation, answer). a) Calculate the volume of water in liters that can be in the pool if it is filled to the brim. b) If we fill the pool only 75%,
- Process 81358
Teo went around the pool twice. He took 160 steps in the process. He took 25 steps along the length. How much area does the pool take up, and how long is Tro's stride? 0.5m?
- Inventory of bottles
Determine the standard inventory of mineral water bottles for smooth operation if the restaurant needs 18,000 half-liter bottles per year. The delivery cycle of goods is 14 days. The minimum insurance stock is set at 5 days. How many liters of mineral wat
- Revolutions of cylinder
The rotating cone has a volume of 120 dm³. How tall is a cylinder of revolution with the same volume as a cone of revolution?
- Cube-shaped 81332
The gardener collects rainwater in a cube-shaped container with an edge length of 80 cm. How many 16-liter buckets will he fill with water from a full reservoir?
- Cities 81317
The cities are 400 km apart; how many cm is it on a 1:400,000 scale map?
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