Math practice for 13 year olds - page 79 of 415
Number of problems found: 8285
- Decorations - spherical
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 mass work
What was the body's mass when it moved along a path of 70 dm and did 1.4 kJ of work? - Diode forward resistance
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? - LED series resistor
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 5 V. - Selection 4
Select the triangle that is similar to the given triangle RTG. △RTG: r = 24 dm, t = 28 dm, g = 30 dm. △SHV: s = 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: - Motor efficiency power
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). - Dice in a box
In a box in the shape of a cuboid, four kinds of dice are stored in four layers. In the first layer there are dice with an edge length of 12 cm. In each subsequent layer the length of the edge of the die is 2 cm smaller than the length of the edge of the - 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 - Number fivefold threefold
Find a number whose fivefold is 8 greater than threefold. - Triangle similarity selection
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 - Cube tower ways
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 cubes are indistinguishable, and so are blue cubes. - Triangle similarity decision Decide whether the triangles are similar. Choose between Yes/No. ∆ YUO: y= 9 m, u= 17 m, o= 12 m, ∆ ZXV= z= 207 dm, x= 341 dm, v= 394 dm
- Aja book pages
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
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? - Perpendicular roads
Two roads meet at a right angle. On one road there is place P at 5 km from the intersection, on the other road there is place R at 12 km from the intersection. Places P and R are connected by a direct path. A pedestrian goes from place R to place P along - 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 - Base and legs
A right triangle has a base/legs/length of 12 cm, and the angle with the hypotenuse is 13 degrees. What is the length of the second hypotenuse? - Identical loaves of bread
If the clerk at the buffet bought 15 identical loaves of bread, she would have 5 euros left in her wallet. If she bought 3 loaves of bread less, she would have 8.60 euros left. How many euros did she have in her wallet? - Power fraction expression
5 to -11 times 5 to -7/5 to zero times 5 to -15 minus ( -5 ) to -2 - Car intersection speed Two cars started from the right-angled intersection of two roads. The first at a speed of 80 km/h and the second at a speed of 60 km/h. How fast are they moving away from each other?
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