Maths practice for 12-year-olds - page 287 of 347
Number of problems found: 6932
- Engine pulley
The engine has a 1460 rev/min (RPM). The disc diameter is 350 mm. What will be the peripheral disc speed in RPM? Pulleys on the engine have a diameter of 80 mm, and a disc has a diameter of 160 mm. - Butterfly flight distance
The death's-head hawkmoth flies at a speed of 50 km/h. They will move to us from Africa in 3 and 3/4 days. How many kilometers will it fly on this journey? - Cylinder twice
If the radius of the cylinder increases twice, and the height is reduced twice, then the volume of the cylinder increases (how many times?): - Tank full
Two hl of water were poured into a block-shaped tank with dimensions of 450 mm and 600 mm and a height of 900 mm. How many liters of water need to be added to keep the tank full? - Diamond height
Calculate the height of a diamond with a circumference of 21.6 cm and an area of 21.6 cm squares. - Cities distance
The bus from Prague to M. Lázně travels at a speed of 36 km/h. At the same time, a car left Mariánské Lázně in the direction of Prague at a speed of 52 km/h. After the 90-minute journey, the two vehicles are still 30 km apart. What is the distance between - Copper plate
Calculate the thickness of the copper plate with a density of 8.7 g/cm³ measuring 1.5 meters and 80 cm, and its weight is 3.65 kg. - Blueberries
Adéla sells blueberries for 50 CZK/1 l, and Zdeněk sells 1 kg of blueberries for 75 CZK. Which of them sells irritants if 1 liter of blueberries weighs 650 g? - Digit sum
Find the smallest natural number n, the digit sum of which equals 37. - Ratios
Reduce the numbers: 50 in a 1:2 ratio 111 at a ratio of 2:3 70 at 10:50 560 at a ratio of 3:8 - Road cleaning
Eight workers in 6 days sweep 2400 m² roads. How many m² will six workers clean in 4 days? - Orchard ratios
One gardener has 8 apple trees and 2 pears in his set. The other gardener has 12 apple trees and 3 pears in his set. a/ which gardener has more apple trees per pear? b/ what is the ratio of apple and pear trees in individual orchards? - Angle subtraction
Calculate: 127 ° 37 '- 58 ° 48' - Face of the house
How tall is the roof of a house in the shape of an isosceles triangle with a base length of 8 meters and an arm 5 meters long? - Milk cans
Two cans hold 20 liters of milk. If we pour from one-sixth to the other, both cans will be the same. How much milk is in each can? - The glass
The glass has the shape of a cylinder with an inner diameter of 12 cm, and the height from the bottom is 16 cm. The cut skewer can be inserted diagonally into the glass so it does not protrude beyond the edge. What is the largest possible length of the cu - Preparatory test
Less than 50 pupils go to 9A class. A third of the pupils wrote the preparatory test with a one, a quarter with a two, no one wrote with a three, and nine pupils with a four. How many students from 9A wrote the test with a five? - Ratio expressions
Express as a ratio: a/ There are 200 boys and 300 girls in the school. b/ The number of chocolates eaten will triple on Nicholas Day. c/ During the holidays, the number of bus passengers decreased by a quarter. - Flower bouquets
No flower will remain if the gardener binds bouquets of 3, 4, and 6 flowers. If she ties a bouquet of 7 flowers, two are missing. How many flowers does a gardener have? - Catheti
One of the catheti of the right triangle has a length of 12 cm. At what distance from the center of the hypotenuse is another leg?
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