Math practice for 13 year olds - page 64 of 435
Number of problems found: 8682
- Corresponds 82534
A current of 0.1 A can lethally affect a human body with a resistance of 3 kΩ. What voltage corresponds to this current? - Resistance 82533
A current of 275 mA passes through the filament of a light bulb with a resistance of 800 Ω. What voltage is the bulb connected to? - Two-digit 82521
Karel had to multiply two two-digit numbers. Out of care, he changed the order of the digits in one of the factors and got a product that was 4,248 less than the correct result. What is the correct result? How much should Karl have earned? - Peripheral 82517
Calculate the peripheral speed of the number on the Wheel of Fortune if the wheel rotates within a period of 0.25 seconds and the number is written 1.5 m from the center of the wheel. - Electrical 82513
How long will it take for a current of 8A in a resistance of 30 ohms to develop thermal energy of 3 MJ if the efficiency of converting electrical energy into heat is 90%? - Subtracted 82507 I think two numbers. Their ratio is 5:7. If 3 is subtracted from the first and 7 from the second, then the ratio is 6:7. What number was I thinking?
- Greatest 82502
In triangle ABC, side a = 30 cm b = 7 cm. The length of the third side in cm is a natural number. What is the least and what is the greatest length that side c can have?
- ABCDEFGH 82499
In the cube ABCDEFGH, the area of triangle ABK is √20 cm². How much cm² is the volume of ABGH in a cube if you know that K is the midpoint of edge CG? - Tetrahedron 82497
The sum of the lengths of all the edges of the regular tetrahedron ABCD is 48 cm. How many cm is the segment XY if you know that X is AB's midpoint and Y is CD's midpoint? - Calculate 82490 Calculate the area of an isosceles triangle ABC with a base of 10 cm and a side of 7 cm. Sketch a picture.
- Circumference 82489
An isosceles trapezoid has one base twice as short as the other. Its area is 42 cm², and its height is 4 cm. Calculate its circumference if you know that the arm is 5.3 cm long. - Perpendicular 82488
For the volumes of a perpendicular prism and a pyramid with the same base and height: A) the volumes are equal B) the volume of a pyramid is three times smaller than the volume of a prism C) the ratio of the volumes of the prism and the pyramid is 1:3 D) - Incorrectly 82480
Peter solves 40 examples. For a correctly solved example, he receives CZK 5 from his mother. For example, in a poorly solved case, he will pay 20 CZK to his mother. After solving all the examples, he had CZK 25 more than when he started counting. How many - Denominations 82479
CZK 8,000 was paid out in fifty pieces of banknotes in denominations of CZK 100 and CZK 200. How many were there? - Perpendicular 82473
In the right triangle KLM, the hypotenuse l = 9 cm and the perpendicular k = 6 cm. Calculate the size of the height vl and the line tk.
- Determine 82470
The school building casts a shadow 16 m long on the plane of the yard, and at the same time, a vertical meter pole casts a shadow 132 cm long. Determine the height of the building. - Cone-shaped 82466
The cone-shaped glass has a volume of 2.5 dl and a diameter of 13 cm. How much cocktail is left in the glass if the level only reaches half the height of the glass? - Segment 82462
I will reduce a segment of length 16 cm in the ratio 7:8, what will its length be in cm? - Difference 82461
Determine the difference in angular velocities of the clock hands. [rad/s] ω of clock hands =? ω minute hands =? ω second hands =? - Diagonal of a cube
Calculate the volume of a cube with a wall diagonal of u = 20 cm.
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