Math practice for 13 year olds - page 198 of 431
Number of problems found: 8620
- The tourist
The tourist walked a quarter of the way on the first day, a third of the rest on the second day, and 20 km on the last day. How many kilometers did he walk in three days? - The cube
The cube has a surface area of 216 dm². Calculate: a) the area of one wall, b) edge length, c) cube volume. - Two-thirds 25651
Two-thirds of the school's pupils went on a trip, one-sixth went on an excursion, and 30 pupils stayed while cleaning the school. How many students attend school? - Calculate 25621
Calculate the area of a regular hexagon inscribed in a circle with a radius r = 7 cm. - A farmer's heritage
A farmer died, leaving his 17 horses to his three sons. When his sons opened up the testament and read: My eldest son should get 1/2 (half) of the total horses; My middle son should be given 1/3rd (one-third) of the total horses; My youngest son should be - Six workers
Six workers earned a total of CZK 12,600 per week on the construction site (5 working days). How much do seven workers earn in 10 days with the same daily average salary? - Quadrilateral prism
The surface of the regular quadrilateral prism is 8800 cm2, and the base edge is 20 cm long. Calculate the volume of the prism
- TV tower
Calculate the height of the television tower if an observer standing 430 m from the base of the tower sees the peak at an altitude angle of 23°. - The ladder
The ladder touches a wall at the height of 7.5 m. The angle of the inclination of the ladder is 76°. How far is the lower end of the ladder from the wall? - Simultaneously 25481
When and where will two trains that run simultaneously from stations A and B at a distance of 60 km meet if the train from station A ran at 70 km/h and the train from station B at 50 km/h? - Insulating 25471
The septic tank is 6 m high and 2.4 m in diameter. If the painter consumes 1 kg per 5 m² and the paint is delivered in two kg cans, how many packages of insulating paint must he order? - Cutting cone
A cone with a base radius of 10 cm and a height of 12 cm is given. At what height above the base should we divide it by a section parallel to the base so that the volumes of the two resulting bodies are the same? Express the result in cm. - Telegraph poles
The bases of two adjacent telegraph poles have a height difference of 10.5 m. How long do the wires connect the two poles if the slope is 39° 30’? - Surface of pyramid
A regular quadrilateral pyramid has the height of the sidewall equal to the length of the edge of the base. The area of the sidewall is 32 cm². What is the surface of the pyramid? - Calculate - prism
The base of the prism is a square with a side of 10 cm. Its height is 20 cm. Calculate the height of a pyramid with a square base of 10 cm, which has four times the prism's volume.
- The observer - trees
The observer sees the tops of two trees at the same angle α. It is 9 m from one tree and 21 m from the other. The trees stand on a level. How tall is the second tree if the height of the first is 6 m? Remember that the eyes of a standing person are approx - Parallelogram 25371
A parallelogram with a side length of 5 cm and a height to this side length of 4 cm has the same area as an isosceles triangle with a base length of 5 cm. What is the height of this triangle? - Calculate 25321 Calculate the body's volume, consisting of a prism and a pyramid with the same square base with an edge of 8 cm. The prism is 20 cm high, and the pyramid is 15 cm.
- Electric work
Calculate the work done by the electric forces passing the current of 0.2 A through the bulb in 10 minutes if the bulb is connected to a 230 V power supply. - Two resistors
Two resistors, 20 Ω, and 60 Ω, are connected in series, and an external voltage of 400 V is connected to them. What are the electrical voltages on the respective resistors? Please comment!
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