Maths practice for 12-year-olds - page 190 of 352

Number of problems found: 7033

Snack
The teacher paid CZK 450 for a snack for 30 pupils. How many CZK will we pay for the same snack for 28 pupils?
Compressive 18853
The granite cube with an edge length of 1 dm and a weight of 2.5 kg is immersed in a container with water. How much buoyancy makes it lighter? How much compressive force does the cube exert on the bottom of the container?
Hydrogen 18823
I have 1 liter of 9% hydrogen peroxide, making it a 3% solution. How much water do I need to add?
Simultaneously 18813
2 ships sail simultaneously towards each other from places 2340m apart. I sail both ships at a constant speed. The first boat travels 56m per minute, and the second 74m per minute. Create an equation that corresponds to the assignment of the task if the u
Dimensions 18793
The rectangle has 10 and 8 cm dimensions on a 1:10 scale plan. How many times does it have more area than on the plan?
Bricklayers 18773
According to the standard, we calculated that two masons would plaster the corridor of the new school building in 54 hours. How long would it take for nine bricklayers to plaster this corridor?
The oil tank
The oil tank in the factory hall has the shape of a cylinder 8 m high and 4 m in diameter. It is three-quarters full. How much oil is in it?
Consumption 18743
With the consumption of 0.4 t of coal per day, the supply lasts for 36 days. How many days will the supply be enough if 16 kg of coal is used less daily?
Approximately 18733
Last year, Mirek's aunt dried 4.8 kg of fallen apples from 30 kilograms of fallen apples. He wants to dry the crosses from 50 kilograms of apples this year. Approximately how many kg will he gain?
An example
An example is playfully for grade 6 from Math, and I don't know how to explain it to my daughter when I don't want to use the calculator to calculate the cube root. Thus: The student made a cuboid from a block of 16x18x48 mm of plasticine. What will be th
Harvesters 18633
Rope wheat harvests seven combine harvesters in 5 days at total capacity. The weather forecast is required to complete the harvest in 4 days. How many combined harvesters had to be used together?
One-fifth 18623
One-fifth of the girls are honored in the class, and the remaining eight girls are doing well. How many girls are in the class?
Branches 18533
The right triangle has an area of 225 cm². One of its branches is twice the size of the other. Find the lengths of its hangers.
One-fifth 18523
The farmer crossed the daily plan to sow wheat by one-fifth and sow in an 11.4 hectare field. Calculate his daily schedule.
Reducing
Reducing the unknown number by 427, we get 65% of its value. What is an unknown number?
Students 18463
There are x girls and nine boys in the class. Write a formula for the number y of all students in the class. Express the number of girls from the formula.
Two rectangular boxes
Two rectangular boxes with dimensions of 5 cm, 8 cm, 10 cm, and second of 5 cm, 12 cm, and 1 dm will be replaced by a single cube box of the same cubic volume. Calculate its surface.
Fifteen 18403
Fifteen ants bring 10 g of food to the anthill in 1 hour. In how many hours will five ants carry 1 kg of food?
The largest
We cut the largest possible cylinder from a 20 cm cube. What is the volume of this cylinder?
What 18373
What is the edge size of a cube with an area of 37.5 m²?

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