Math practice for 13 year olds - page 74 of 434
Number of problems found: 8666
- Spherical 81527
Sketch a spherical layer formed from a sphere with a radius of r= 8.5cm, given: v=1.5cm, r1=7.7cm, r2=6.8cm. What is its volume? - Children 81526
There are 32 children in the class. If there were three more boys and one less girl, there would be an equal number of girls and boys in the class. How many boys are there in the class? - Savings 81523
The savings of Vlad and Peter are in the ratio of 15:8, and the savings of Peter and Juraj are in the ratio of 2:1. What is the ratio of the savings of Vlad, Petr, and Juraj? - Glasses 81522
5 out of 32 plates and 2 out of 20 glasses were broken at the party. What is the ratio of plates to glasses now? - Together 81521
Pavel and Vojta were planting trees at the forestry brigade. Pavel planted two more trees than Vojta in a six-hour shift. Together, they planted 156 saplings in three such shifts. How many saplings did Pavel and Vojta plant during the brigade? - Diamond-shaped 81516
How many diamond-shaped tiles with a side of 25 cm and a height of 20 cm are needed to pave a rectangular courtyard with sides of 30 m and 28 m if the joints represent 1/20 of the area? - Decorations 81510
The glass Christmas decorations have the shape of a ball with a diameter of 8 cm. In a small family business, they produce 50,000 pieces a year. The entire surface of these balls is covered with glitter. 400 g of glitter is needed to cover an area of 1 m²
- Body's 81509
What was the body's mass when it moved along a path of 70 dm and did 1.4 kJ of work? - Resistance 81503
What is the value of the resistance of the rectifier diode in the forward direction if the current IF = 5 A flows through it and the voltage between the anode UF = 820 mV? - Resistor 81502
How big a series resistor do we need to connect to the LED if a voltage drop of 3.2 V is to be created on it and a current of 16 mA flows through the diode? We want to connect the diode to a voltage of 5V. - Selection 4
Selection triangle, which is similar to the given triangle RTG. ∆ RTG, r= 24 dm, t = 28 dm, g= 30 dm. ∆ SHV= 6 dm, h= 7.5 dm, v= 7 dm ∆ VSH= v= 7 dm, s= 6 dm, h= 7.5 dm ∆ HVS= h= 7.5 dm, v= 7 dm, s = 6 dm. ∆ VHS= v= 7 dm, h = 7.5 dm, s= 6 dm. ∆ HSV= h= 7. - Horsepower 81496
The electric motor has an efficiency of 80% (power and input ratio). What is the power input of this motor if its power is 5 horsepower (HP)? Enter the result in kilowatts (kW) and round to one decimal place (1 HP = 3/4 kW). - Three-day trip
George went on a moped for a three-day trip. He drove 90 km on the first day, 30 km on the second day, and 60 km on the third day. He always drove at the same average speed and always the whole number of hours. Calculate the average speed if George drove - Threefold 81491
Find a number whose fivefold is 8 greater than threefold. - Triangle 81484
Choose a triangle that is similar to the given triangle. - ∆ TFC= t= 8 cm, f= 9 cm, c= 7 cm. : ∆ PKU= p= 45 cm, k= 35 cm, u= 40 cm. ∆ UPK= u= 40 cm, p= 45 cm, k= 35 cm. ∆ PUK= p= 45 cm, u= 40 cm, k= 35 cm. ∆ KPU= k= 35 cm, p= 45 cm, u= 40 cm. ∆ KUP= k= 35
- Indistinguishable 81481
How many ways can a tower of five yellow and four blue cubes be built so that each yellow cube is adjacent to at least one other yellow cube? Yellow dice are indistinguishable, and so are blue dice. - Triangles 81480 Decide whether the triangles are similar. Choose between Yes/No. ∆ YUO: y= 9m, u= 17 m, o= 12 m, ∆ ZXV= z= 207 dm, x= 341 dm, v= 394 dm
- Fifteenths 81479
Little Aja planned to read the book, which has 120 pages, for 4 days. On the first day, she read a quarter of the whole book; on the second day, she had training and therefore only read two-fifteenths of the book; on the third day, she read seven-twentiet - Archaeologists 81478
Archaeologists need to find out the size of the vessel if the sherd found was in the shape of a circular section with a length of 12 cm and a height of 3 cm. What is the area of this section? - Quadrilateral calc
The square ABCD is given. The midpoint of AB is E, the midpoint of BC is F, CD is G, and the midpoint of DA is H. Join AF, BG, CH, and DE. Inside the square (approximately in the middle), the intersections of these line segments form a quadrilateral. Calc
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