Math practice for 13 year olds - page 321 of 434
Number of problems found: 8665
- Security
The safe's security code is set with three dials. The first dial has five different letters, the second dial has the numbers 0 to 4, and the third dial has the numbers 5 to 9. One code can be set in approximately 1 second. How should the alarm be timed so - Passenger 4468
A truck left Beroun at 7 o'clock in the direction of Prague on the highway in the fog. In 20 minutes after that, a car drove by at the same place and along the same route at a 27 km/h higher speed. The passenger car overtook the truck after another twenty - Time gone
The Square of Richard's age equals the age of his mother. When he is two times older, his mom will be seven times older than him. Thus, Richard and his mom are seven times older. - Right triangle eq2
The hypotenuse of a right triangle is 9 cm longer than one leg and 8 cm longer than the second leg. Determine the circumference and area of a triangle. - Minutes 4465
Peter and Karel live at the same address. Peter will drive to the stadium in 30 minutes and Karel in 40 minutes. If Karel goes 5 minutes early, where will Peter catch up? - Sheriff 4462
The cowboy will give the sheriff two bags of oats, and the sheriff will have 2x more bags than the cowboy. If the sheriff gives two bags of oats to the cowboy, they will both have the same. How many bags does each have? - Arrangements 4459
There are 4 classrooms on the ground floor of the school building, which are numbered 1,2,3,4. First-year students A, B, C, and D will be placed in these classrooms. Write all possible class arrangements and their number. Thank you
- Calculate 4457
Calculate how many trees are in an orchard if you know that 5/12 orchards consist of apple trees, 1/6 plums, and 1/60 walnuts. The remaining 30 trees are pear trees. - 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
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