Math practice for 13 year olds - page 285 of 420
Number of problems found: 8399
- Excavation by gentlemen
The site manager, based on the length of the excavation, estimated that the whole excavation for laying a plastic pipe bringing water to the kindergarten building could be carried out by Mr. Demeter together with Mr. Vondrák in 1.2 shifts. From experience - Music Recording Duration
Fifty-six seconds have already elapsed from the music recording, which was 14% of the total duration of the recording. How long the recording will still last. - R1+R2 in parallel
The resistance ratio of the first and second resistors is 3:1, and the current flowing through the first resistor is 300 mA. What current flows through the second resistor (resistors connected in parallel)? - Voltage Ratio in Series If the resistance of the first resistor is 200 ohms and the resistance of the second resistor is 600 ohms. What will be the ratio of the electrical voltage across the first resistor to the electrical voltage across the second resistor (both are connected
- Resistors Series Voltage Ratio If the resistance of the first resistor is 100 ohms and the voltage ratio on the first and second resistors is 2:1. What will be the resistance of the second resistor connected in series?
- Sum of squares
The sum of squares above the sides of the rectangular triangle is 900 cm². Calculate the area of the square over the triangle's hypotenuse. - Fractions
Three-quarters of an unknown number is 4/5. What is 5/6 of this unknown number? - Individual
On a hill behind Terchová, there is a sheepfold where a shepherd lives. He divided his two hundred sheep into 4 groups in a mysterious way: If he had 4 more sheep in the first group, 4 fewer in the second, 4 times more in the third, and 4 times fewer in t - Filling Tank Together
The tank will be filled with the first inlet in 5 hours and the second in 12 hours. How long would it take to fill the tank together? - Candies Eaten Fractions
Walter ate 1/5 of the candies. Mark ate 1/3 of the sweets, and Susan ate 21 candies. How many candies were together? - Apple price calculation
When you buy 3 kg of apples and 2 kg of oranges, we will pay € 12. When you buy 2 kg of apples and 4 kg of oranges, we pay € 16. How much does 1 kg of apples cost? - Cost of Wooden Boards
How much do we pay for 15 pieces of boards 6 m long, 15 cm wide, and 25 mm thick if 1 m³ of boards costs 130 €? Round the price to the whole of €. - Ice cream maker
Ice cream maker Eda has invented a new cone in the shape of a regular four-sided pyramid, in which he will sell his ice cream. The cone will have a lateral edge length of 5 cm and a slant height of 4 cm. In order to mass-produce it in a factory, the dimen - Spiders and Beetles Legs
The boy establishes collections of spiders and beetles. So far, he has only a total of 8. When asked how many beetles he has, he replied: "My entire collection has 54 legs. "How many spiders and how many beetles? - Resistor Current Ratio Parallel
If the resistance ratio of the first and second resistors is 3:1 and the current flowing through the first resistor is 300 mA. What will be the current through the second resistor? - Serial connection If the voltage on the first resistor is 6 V and the resistance ratio of the first and second resistors is 1:3, what will be the voltage across the second resistor if they are connected in series?
- Last storm - tree
Mr. Radomír had a misfortune during the last storm; a tree fell on his roof in the shape of a regular four-sided pyramid and destroyed it all. The roof has a base edge length of 8 m and a side edge length of 15 m. How many m² of roofing will he have to bu - Resistor Ratio in Parallel If the current flowing through the first resistor is 200 mA and the second is 0.4 A, what will be the ratio of the first and second resistors connected in parallel?
- Electric motor power
A current of 2 A at a voltage of 400 V passes through the electric motor. The electric motor is switched on for 0.5 h. What is the power input of the electric motor? - Bulb
A 60 W bulb consumes 0.12 kWh of electricity. How long did she stand light without a break?
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