Maths practice for 12-year-olds - page 55 of 355
Number of problems found: 7081
- Movie time remaining
The whole movie lasts 1 hour. The time left until the end of the film is half of the time that has already passed since the film's beginning. Calculate how many minutes are left until the end of the movie. - Milk butter kilograms
8 kg of butter is made from 20 hl of milk. How many kilograms of butter can be made from 450 l of milk? - Steel rope weight
Calculate the weight in kg of a steel rope 1.5 cm in diameter and 10 m long if one cubic centimeter of steel weighs 7.8 g - Car kinetic energy
Determine the kinetic energy of a car with a mass of 800 kg if it travels at a speed: a) 10 m/s b) 20 m/s - Body kinetic work
What work must be done to bring a body of mass of 2 kg lying on a smooth horizontal plane from rest to a speed of 2 m/s? - Vinegar acetic acid
Kitchen vinegar is an 8% solution of acetic acid in water. How many liters of acetic acid are needed to produce 275 liters of vinegar? - Jožko animal count
Jožko keeps dogs, guinea pigs, hamsters, and hares. A total of 24 animals. Of these, 1/3 are hamsters, 3/8 are guinea pigs, and 3/4 are not hares. How many dogs does Jožko have? - Teacher paper correction The new teacher corrects papers for 9 hours, and the older one fixes them in 6 hours. How much will they repair together?
- Class height average
There were 21 pupils in the class, and arithmetically, the average height of these pupils was 163 cm. Calculate what the average height in the class will be if: a) A 159 cm tall student was added to the class b) A 169 cm tall student left the class - Brass copper zinc
Brass is an alloy of copper and zinc in a ratio of 3:2. How much copper and zinc do you need to make 1 kilo of brass? - Car textbook pursuit
At 9 a.m., a truck with textbooks left Brno at a speed of 50 km/h; at 9:30 a.m., a passenger car left Brno with another delivery of textbooks at a speed of 70 km/h. When will the passenger car catch up with the truck? - Train freight meeting
A passenger train will travel from Brno to Bratislava (144km) in 3 hours; a freight train will cover this distance in 4.5 hours. How long will they meet if a passenger train from Brno and a freight train from Bratislava leave simultaneously? How many kilo - Bronze figurine alloy
The bronze figurine weighs 0.5 kg. Bronze is an alloy of tin and copper in a ratio of 1:4. How many grams of copper and how many grams of tin does the statuette contain? - Squirrel acorn supply
A supply of acorns will last a squirrel for 12 weeks and a squirrel for 18 weeks. They ate acorns together for 4 weeks, then the squirrel left. How long did the squirrel have a supply of acorns? - Number sum divisibility
Adam wrote the following sum with five secret adders: a + bb + ccc + dddd + eeeee. He revealed that the characters "a, b, c, d, e" represent the different digits 1, 2, 3, 4, and 5 and that the resulting sum is divisible by 11. Which is the smallest and wh - Seedling distance reduction
If you plant seedlings in the bed at a distance of 20 cm, 40 will fit here. How many seedlings will fit here if you reduce the distance between them to 15 cm? - Chain color length
Children in the school club made a tricolor chain from crepe paper. One-eighth of the chain is red, three-quarters is olive, and the remaining 20 cm is blue. What length of chain did they make? - Cake price difference
Mom bought three cakes at the pastry shop. The first cost 72 crowns. The second was a quarter cheaper than the first. The third dessert was a third of the total price of all three desserts. By how many crowns was the third dessert more expensive than the - Kangaroo speed minutes
A kangaroo can move at a speed of 65 km/h. How many minutes will it take to move at this speed to a place 6500 m away? - Pool inflow half
The pool has a maximum water capacity of 1200 hl. How many hours will the pool be half complete if the first inflow is 200 l per minute and the second 100 l per minute?
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