Math practice for 13 year olds - page 178 of 428

Number of problems found: 8555

Bronze alloy
Bronze is an alloy of tin and copper. Copper is 85% the rest is tin. How much bronze do we make from 51 kg of copper? Will 8 kg of tin be enough for us?
Equilateral triangle v3
Calculate an equilateral triangle's perimeter and area with a side of 20 dm.
Worker production
Eight workers produce 2048 products per shift. In how many hours would ten workers produce the same amount of products? (shift is 8 hours)
Prism height
What is the height of a prism with a right triangle base and sides of 6 cm and 9 cm? The hypotenuse is 10.8 cm long. The volume of the prism is 58 cm³. Calculate its surface area.
Tank water comparison
We have two cube-shaped tanks. The first has an edge of 12 dm long, and the second has an edge of 20% longer. By what % more or less water is there in the second tank if the first is three-quarters full and the second three-eighths full?
The notebook
The notebook cost 10.50 euros after rising by 40%. How much would it cost if it increased in price by only 20% instead of 40%?
Buoyancy force
An adult male has a volume of about 0.070 m³. How much buoyancy affects him when he is completely immersed in water?
Sugar solution percentage
Mix 0.8 kg of sugar into 2.4 kg of water. What percentage of sugar solution do we get?
Five-digit number creation
How many different five-digit numbers can we create from digits 4 and 5?
Current injury protection
1. Describe the path through which the current causing the injury flows. 2. Justify why we should use the lowest type of protector A in our country.
Pin circle arrangement
Three circles of the same size are drawn on the playing field. Arrange the 16 pins so that there are 9 pins in each circle. Find at least eight significantly different layouts, i.e. J. such layouts in which pins or circles are not distinguished.
Penalty invoice
The company paid a penalty of 7.5 ‰ for the late invoice payment. How big was the invoiced amount when the company had to pay a fine of 3441 CZK?
Candy mixture price
The saleswoman mixed two types of candies into the cone. Half a kilo of fruit at 90 CZK per kilogram and 400 g of nut at 117 CZK per kilogram. How many crowns will 1 kg of this mixture cost?
Vinegar mixture percentage
What percentage of vinegar do we get by mixing 2 liters of 8% vinegar with 3 liters of 4% vinegar?
Hydrogen peroxide dilution
How much distilled water does a laboratory assistant have to add to 500 ml of 30 percent hydrogen peroxide to prepare a 3% gargle?
Water temperature mixing
The mother prepared half a liter of cold water for the children to drink. It mixed water at 20 °C with 400 ml of cold water at 5 °C. What was the temperature of the prepared drink?
Water temperature mixing
Honza filled 2 liters of hot water at a temperature of 90 °C from a heater into a five-liter container. What temperature must the water that the container fills have a mixture temperature of 42 °C?
Mushroom risotto
630g of rice is needed to prepare mushroom risotto for four people. How many boxes of 500g rice do you have to buy to prepare risotto for 17 people?
Prize distribution
On the Matějska Pilgrimage, they had 40 prizes of two kinds in the wheel of fortune with a total value of 500 CZK. Four pieces of the first were worth CZK 60, and seven pieces of the second kind were worth CZK 80. Determine the number of pieces of each ty
Truck kinetic energy
The truck travels at a constant speed of 70 km/h. The first time it goes empty, and the second time it comes with a load. In which case is its kinetic energy smaller?

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