Maths practice for 14 year olds - page 161 of 370
Number of problems found: 7399
- 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 - Determine 25341
In a two-digit number, the number of tens is three more than the number of ones. If we multiply the original number by a number written with the same digits but in the reverse order, we get the product 3 478. Determine the actual number. - In the dairy
The dairy had three times more milk packages than half a liter. Four times more liters remained when sold in 10 liters and 10 half-liter containers than in half-liter packages. How many packages were there originally? - 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! - Resistances 25281
Three resistors with resistances of 200 Ω, 400 Ω, and 600 Ω are connected next to each other (parallel). A current of 1.8 A flows through the first 200Ω resistor. a) What current passes through the second and what current through the third resistor? b) Wh - Resistances 25271
Three resistors with resistances of 200 Ω, 400 Ω, and 600 Ω are connected in series (in series)—a current of 1.8 A flows through the first 200Ω resistor. a) What current passes through the second and what current through the third resistor? b) What are th - Diamond area from diagonals
In the diamond, ABCD is AB = 4 dm, and the diagonal length is 6.4 dm long. What is the area of the diamond? - Lowest voltage Three resistors with resistors R1 = 10 kΩ, R2 = 20 kΩ, R3 = 30 kΩ are connected in series and an external voltage U = 30 V is connected to them. On which resistor is the lowest voltage?
- Height of pyramid
The pyramid ABCDV has edge lengths: AB = 4, AV = 7. What is its height? - Statistically 25181
Statistically, in a city of 100,000 inhabitants, 600 people die in one year. During the year, 2,000 people received hospital treatment, and 120 of them died there. Calculate the probability that a citizen who comes to the hospital for treatment will die t - Aircraft climbing
The average climb angle of the aircraft is 11° 20', and its average speed is 400 km/h. How long does it take to climb to a height of 3000m? - The rectangle
The rectangle has a circumference of 32 m. One side is 2 m longer than the other side. Calculate the side lengths of this rectangle. - Half-cylinder 25121
How much sheet metal do we use to produce a gutter pipe in the shape of a hollow half-cylinder 20 m long and 16 cm wide if we count 8% for bending and welding? - Everything in soup
The pot with soup is shaped like a cylinder with a bottom diameter of 20 cm and a height of 24 cm. How many guests will we have enough soup for if the pot is filled to two-thirds of the height and 0.25 l of soup is calculated per person? (pay attention to - Circle and square
An ABCD square with a side length of 100 mm is given. Calculate the circle’s radius that passes through vertices B, C, and the center of the side AD. - Mains voltage How much electric current flows through the appliance with a resistance of 40kΩ, connected to the mains voltage (230 V)?
- Resistance 25031
The current of 25 mA passes through the resistor with a resistance of 50Ω. How much voltage do we measure on it? - Resistance 25021
Calculate the resistance and power of the appliance through which a current of 20mA flows at the mains voltage (230 V). - Electric 25011 How much voltage do we measure on a 400Ω resistor when an electric current of 55 mA passes through it?
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