Math practice for 13 year olds - page 338 of 414
Number of problems found: 8279
- Concrete block
Determine the volume of the concrete block whose one edge of the base is 3 meters long, the body diagonal is 13 meters, and the height is 12 meters. - Distilled water
Seawater contains 5% salt. How much distilled water should be poured into 40 kg of seawater so that the salt content is 2%? How many kilograms of 2% of seawater do we get? - Number difference
The difference between the two numbers is 4/3. If you know that the first number is 50% larger than the second number, specify both numbers. - Water temperatures To 25 liters of water at 50 °C, we add 15 liters of water at a different temperature. How many °C should the water be colder than 50 °C so that 40 liters of the water obtained has a temperature of 42.5 °C?
- Acid solution concentration
Calculate the concentration of the solution prepared from 6 kg of 95% sulfuric acid solution and 24 kilograms of 10% sulfuric acid solution. - Formic acid mixture
How many liters of 60% and 80% formic acid do we have to mix to get 80 liters of this acid with a concentration of 65%? - Candy
The price for 1 kg of more expensive candy is 125 CZK. The price for 1 kg of cheaper candy is 100 CZK. We make two different blends of candy. And now. The second blend contains 2 kilograms of more expensive candy and several kg of cheaper candy. The price - Solution dilution
1.5 kg of a 20% NaCl solution should be diluted to a 10% solution with water. How much water will we need, and how many kilograms of diluted solution will we get? - Alcohol mixing
How many liters of 80% alcohol need to be mixed with 4 liters of 40% alcohol to get 70% alcohol? How many liters of 70% solution do we get? - Two numbers sum
The sum of the two numbers is 52.5. The first number makes up 75% of the second number. Specify both numbers. - Solution
What amount of 80% solution and water is needed to mix to obtain two liters of 60% solution of this mixture? - Parallelogram sides
In the parallelogram ABCD, the side AB is three times longer than the side BC. The perimeter of the parallelogram is 20 cm. Find the lengths of the sides of the parallelogram. - Savings distribution
Milo has 84 euros. He gave his brother 20% of his savings and his sister 25%. Find how much money each has. - Two-digit numbers
How many two-digit numbers can you create from the digits 7,0,1 and 5 if the numerals can be repeated? - Mr. John
Mr. John wants to buy winter apples Spartan. There are two ways to buy: 1) buy apples at the marketplace, where 1 kg costs 15 CZK. 2) Bring the car to the agricultural farm, where the apples are sold for 9 CZK per kilogram. However, he must pay CZK 150 fo - Beam on platform
A homogeneous wooden beam of length 6.00 m and mass 72.0 kg lies on a horizontal platform high above the ground and overhangs by 1.80 m over the edge of the platform a) Decide whether a person with a mass of 60.0 kg can stand on the overhanging end of the - Mr. Liška
Mr. Liška decided to replace the floors in some rooms of his flat. a) The kitchen is a rectangle with sides 180 cm and 420 cm. How many square tiles with a side of 20 cm long will he need? b) How many packages of tiles must he buy, if in one package there - Tiles path
A rectangular park measures 24 m X 18 m. A path 2.4 m wide is constructed all around it. Find the cost of paving the path with cement tiles of size 60 cm X 40 cm at the rate of $5.60 per tile. - Digging
A pit is dug in the shape of a cuboid with dimensions 10mX8mX3m. The earth taken out is spread evenly on a rectangular plot of land with dimensions of 40m X 30m. What is the increase in the level of the plot? - Fog
The car started in fog at a speed of 30 km/h. After a 12-minute drive, the fog dissipated, and the driver drove the next 12-minute distance, 17 km. The driving conditions deteriorated during the last 17 km, and the driver drove at 51 km/h. a) Calculate th
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