Math practice for 13 year olds - page 323 of 436
Number of problems found: 8719
- Passengers 4456
A train running at 20 m/s sees passengers through the window for 5 seconds. Another train with a length of 250 m runs on the siding in the opposite direction. Find the speed of the second train. - Antiquarian 4454
How much more expensive is it for the owner to sell a book he bought in an antiquarian book for half the price if he sells it for two-thirds of the original price? - Remaining 4448
3/4 of the class went skiing. Of those who stayed home, 1/3 fell ill, and the remaining 6 were at a math camp. How many students does the class have? - Volume of an apple
How many apples will fit in a box measuring 20 cm × 50 cm × 25 cm?
- Circumference 4430
There is an isosceles triangle with a circumference of 36 cm, and the height at the base is 12 cm long. Calculate the length of the arm of a given triangle. - Percent to number
To increase that number by 5 percent, we need to multiply it by: - Circumference 4421
The area of an equilateral triangle is 81 times three below the square root of cm². Calculate its circumference. - The pipe
The pipe is 1.5 m long. Its outer diameter is 60 cm, inner diameter is 52 cm. Calculate the pipe's weight if the material's density from which it is made is 2 g/cm³. Please round the results to whole kilograms. - The cast
The cast in the body of a regular quadrilateral pyramid with a base edge 60 cm long and 5 cm high is made of a material with a density of 7.8 g/cm cubic. Calculate its weight.
- If we
If we increase the unknown number by 4%, we get 780. Determine the unknown number. - Simultaneously 4412
While hunting, the dog sees a hare in the bushes 20 meters ahead. The hare starts running, and the dog starts chasing it simultaneously. A hare runs at a speed of 39 km/h, and a dog at 45 km/h. In how many seconds does the dog catch up with the hare? - Cylinder-shaped 4411
A cylinder-shaped hole with a diameter of 12 cm is drilled into a block of height 50 cm with a square base with an edge length of 20 cm. The axis of this opening passes through the center of the base of the cuboid. Calculate the volume and surface area of - Cylinder-shaped 4410
A cylinder-shaped case is to be made for a ruler with the shape of a prism with a base in the shape of an equilateral triangle with a side length of 3 cm. What must be the smallest inner diameter of the housing? Determine the size to the nearest tenth of - Ice and water
We want to cover a rectangular rink with dimensions of 55 m and 25 m with a 4cm thick layer of ice. How many liters of water do we need if freezing water increases its volume by 10%?
- Rhombus and diagonals
The rhombus area is 150 cm2, and the ratio of the diagonals is 3:4. Calculate the length of its height. - Materials 4405
Two trucks were supposed to load the building materials in 10 days. After 6 days of work, the first car broke down, and the second one carried building materials for another 9 days. How many days would the first and second cars take the building materials - Rectangular 4402
Our task is to save the rectangular images with dimensions of 105 mm and 42 mm so that we cover the smallest square. What will be its size, and how many pictures do we need? - Apples 2
Dried apples contain 15% water. Fresh apples contain 80% water. How many kilograms of apples must we buy to get 3 kg of dried apples? - Fuel economy
How many kilometers is sufficient petrol in the cylinder fuel tank with a diameter of 40 cm and the base of tank length of 1 m when it is filled to 60%, and if the car consumes 15 liters per 100 km?
Calculate the side of a square when its diagonal is 10 cm.Do you have unsolved problem that you need help? Ask a question, and we will try to solve it. Solving math problems.
