Maths practice for 12-year-olds - page 169 of 361
Number of problems found: 7204
- Brass sphere
Find the weight of a brass ball with an outer radius of 12 cm and a wall thickness of 20 mm if the brass's density is 8.5 g/cm³. - Thousand balls
We must create a thousand balls from a sphere with a diameter of 1 m. What will be their radius? - Insulation
A special rubber pipe protector is used to insulate the supply pipes of solar collectors. The product with the description DNa20, thickness 25 mm, 2 m, corresponds to insulation for pipes with a diameter of 20 mm with a rubber layer thickness of 25 mm, wh - Vertical 29801
The shadow of the building is 16 m long, and the shadow of the vertical meter rod is 0.8 m long at the same time. What is the height of the building? - Triangular 29781
A triangular building plot is drawn on a 1:5,000 scale plan as a triangle with sides of lengths 32.5 mm, 23.5 mm, and 36 mm. Determine how many m of mesh are needed to fence the entire plot. - Hectares
The rectangular land has 3 cm and 4.5 cm dimensions on the plan with a scale of 1:40,000. Find the area of the land in hectares. - Consecutive 29761
Determine three consecutive natural numbers, the sum of which is 66.
- Worker salary
The worker had a salary of CZK 18,000. During the year, his salary was increased by a quarter. He earned a total of CZK 247,500 for the whole year. From which month was his salary increased? - Volume of sphere
How many times does the volume of a sphere increase if its radius increases two times? - Cylindrical tank
9.6 hl of water is poured into a cylindrical tank with a bottom diameter of 1.2 m. What height in centimeters does the water reach? - The string
They cut 113 cm from the string and divided the rest in a ratio of 5:6.5:8:9.5. The longest part measured 38 cm. Find the original length of the string. - Extending square garden
Mrs. Petrová's garden had a square shape with a side length of 15 m. After its enlargement by 64 m² (square), it became a square again. How many meters has the length of each side of the garden been extended? - Gears
The front gear on the bike has 32 teeth, and the rear wheel has 12 teeth. How many times does the bike's rear wheel turn if you turn the right pedal 30 times? What distance will you go if the circumference of the bicycle wheel is 250 cm? - Olive seeds
5 kg of oil is pressed from 100 kg of seeds. How many kgs of seeds do we need to produce 85 kilograms of oil? - Change the length
Change of line MN, MN = 4.7 cm in the ratio 5:3.
- Poplar shadow The nine-meter poplar casts a shadow 16.2 m long. How long does a shadow cast by Peter at the same time if it is 1.4 m high?
- Fabric 29531
To sew a dress, you need 2 meters of fabric 150cm wide. How many meters of cloth do we need for the same dress if the fabric is only 90 cm wide? - Christmas 29521
In the autumn, the school canteen bought 50 kg of apples for 12 CZK. If the apples already cost 20 CZK, how many kilograms of apples could they buy before Christmas for the same amount? - A family
A family of four consumes 220 liters of water a day. How many hectoliters of water are consumed by 68 tenants per day? - Minutes 29491
The car will drive 70km in 56 minutes. How many meters will he drive in half an hour?
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