Math practice for 13 year olds - page 287 of 431
Number of problems found: 8620
- 14-carat 5956
14-carat gold. ... .585 per mille. In one kg. ... .585g gold. If the weight of pure gold in a ring is 7.2g, how much does the ring weigh? - Original price
The dress was reduced by 20% and, after another six months, by another 5%. It now costs 38 EUR. What was the original price of the dress? - Expressions 5949
The expressions A = 8x + 17, B = -12x-12, C = 9x-10 are given. Two-fifths of the sum of expressions A, B, and C are equal ... - Fifty-six 5943
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)? - Resistance 5939 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
- Resistance 5938 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? - Minutes 5934
The thief stole Peter's bike and rode it down the road at 25 km/h. Peter's older brother saw it in half a minute and caught up with the thief in 5 minutes on the second lap. How fast must Peter's brother have been driving? - Individual
On the hill behind Terchová, there is a sheepfold and a shepherd lives in it. He divided two hundred of his 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 l - Distribution 5932
One-half of the turnover is used for wages and one-third for production and distribution. After postponing CZK 100,000 for marketing, CZK 230,000 will remain. How high is the total turnover? - Together 5931
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? - Together 5930
Vlado ate 1/5 of the candies. Marek ate 1/3 of the sweets, and Susan ate 21 candies. How many candies were together? - Kilometers 5928
The tourist traveled 78 km in three hours. For part of the journey, he traveled by bus at an average speed of 30 km/h, and for the rest, he walked at an average speed of 6 km/h. How long did he walk, and how many kilometers did he walk?
- Oranges 5927
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? - Boards 5926
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 nice cone in the shape of a regular four-sided pyramid, in which he will sell his ice cream. The cone will have a side edge length of 5 cm and a wall height of 4 cm. In order to mass-produce it in the factory, they s - Establishes 5921
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? - Resistance 5920
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?
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