Math practice for 13 year olds - page 192 of 434
Number of problems found: 8665
- Screws
The box contains eight iron, six brass, and four titanium screws. What is the probability that the randomly selected screw will not be brass?
- Students
Students solve word problems. They received 3 points for each correctly solved task. Four points were deducted for a task that was not solved or incorrectly solved. Tomas solved a total of 15 tasks and scored 24 points. How many tasks did he solve correct
- Quadrilateral 29201
How much sheet is needed for a roof with the shape of a regular quadrilateral pyramid if its edge is 2.8 m long and the height of the roof is 0.8 m? Calculate 10% for the overlap (extra).
- Diggers
Eight diggers will do the job in 85 hours. After 21 hours, three diggers had to leave. How many hours will the work be done?
- Hexagonal pyramid
Calculate a regular hexagonal pyramid's volume and surface area with a base edge a = 30 m and a side edge b = 50 m.
- Probability 29163
There are ten red, six blue, and eight green balls in the hat. What is the probability that a randomly selected ball is blue or red?
- Quadrilateral pyramid
The height of a regular quadrilateral pyramid is 6.5 cm, and the angle between the base and the side wall is 42°. Calculate the surface area and volume of the body—round calculations to 1 decimal place.
- Hexagonal 29141
Calculate the volume and surface of a regular hexagonal prism with a base edge a = 30 m and a side edge b = 50 m.
- Diagonal BD
Find the length of the diagonal BD in a rectangular trapezoid ABCD with a right angle at vertex A when/AD / = 8,1 cm and the angle DBA is 42°
- Inclined plane
The body stays on an inclined plane and exerts a compressive force of 70N on it. Find the angle between the inclined plane and the horizontal if a gravitational force of 100N acts on the body.
- The leaves
Karel raked the leaves in the garden alone in 24 minutes, and his younger brother took 30 minutes. How long would they dig a garden if Karel digs alone for 6 minutes and his brother comes to his aid?
- Kindergartens 29031
We bought 50 kindergartens of two types for the kindergarten - milk for 16 CZK per piece and hazelnuts for 11 CZK per piece. We paid a total of CZK 700. How many chocolates were there?
- Fulfilled 29001
Race A can fulfill the order in 12 days, and race B can fulfill the same order in 18 days. If both plants work together, how many days will the order be fulfilled?
- Chimney and tree
Calculate the height of the factory chimney, which casts a shadow of 6.5 m long in the afternoon. At the same time, a 6 m high tree standing near it casts a shadow 25 dm long.
- Sound speed in Earth
Through the surface layers of the Earth, sound propagates 13 times faster than through air. The charge exploded 1.7 km from the measuring station during the geological survey. How long does it take between the measuring point's soil vibration and the mome
- Magic bag
The number of tolars in the magic bag doubled each time the prince crossed the bridge. But then the devil always conjured 300 tolars for him. When this happened for the third time, the prince had twice as much as he had in the beginning. How many tolars d
- The regular
The regular triangular prism has a base in the shape of an isosceles triangle with a base of 86 mm and 6.4 cm arms; the height of the prism is 24 cm. Calculate its volume.
- Similar triangles
Triangle A'B'C 'is similar to triangle ABC, whose sides are 5 cm, 8 cm, and 7 cm long. What is the length of the sides of the triangle A'B'C' if its circumference is 80 cm?
- Traveling 28813
The ship set sail at 6 A.M. and traveled at a speed of 16 km per hour. At 8:30 A.M., a speedboat was sent behind her, traveling 24 miles per hour. When will the boat catch up?
- Big numbers
How many natural numbers less than 10 to the sixth can be written in numbers: a) 9.8.7 b) 9.8.0
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