Math practice for 13 year olds - page 68 of 420
Number of problems found: 8392
- Inscribed cube
A cube is inscribed in a sphere with a radius of 27 cm. Calculate its volume and surface area. - Small density cube
Calculate the mass of a cube with an edge of 15 cm made of oak wood with a density of ρ = 800 kg/m³. - Increased 81943
The mobile was increased by a quarter of the original price and then again by a quarter of the new price. How much did the mobile cost if its final price was 125 euros? - Consumption 81941
The car consumes up to 16 l in the city, but on a longer trip, the consumption drops to 10 l? 500 km per month in the city and 1650 km outside the city. What is the consumption of a car per 100 km? - Calculate 81939
The block surface is 5,632 m². The lengths of the edges are in the ratio 1: 2 : 3. Calculate the volume of the cuboid. - Increased 81938
We increased the side of the square by 12% from the original 15cm. For a, what was the perimeter and area of the new square? By what percent did the perimeter and area increase? - Cantilevers 81937
Calculate a prism's volume and surface area with a base of a right triangle with cantilevers of length 40 and 43 cm. The height of the prism is 60 cm. - Cube-shaped 81931
A ball with a diameter of 10 cm is in a cube-shaped box with an edge of 10 cm. What percentage of the box does the ball fill? - Distribution 81926
There are 28 pupils in the class. Twenty-seven of them wrote the control paper in mathematics. Four students had a one, 8 had a two, 12 students had a three, and 3 had a four. Express this distribution as a percentage. - Subtracting 81925
Three horses will eat 36 kg of oats in two days. How many kilograms do 5 horses need for 4 days? Help yourself by adding or subtracting. - Important 81924
Karel went for a walk at a speed of 5 km/h. After 3 hours, Ondra rode to him with an important message. He was moving at a speed of 20 km/h. How many minutes did Ondra catch up with Karel? - Foresters 81919
Foresters planted 2,440 saplings in three days. On the second day, they planted 20% more saplings than on the first day, and on the third day, 15% less than on the first day. How many saplings did the foresters plant each day? - Observatory's dome
In our city, they decided to reconstruct the observatory's dome and cover it with sheet metal. At least how many square meters of sheet metal will they need if the dome is in the shape of a hemisphere with a diameter of 6m? - Custom-made 81913 On October 1, 2022, the customer ordered a custom-made kitchen from a carpentry company. Delivery time is 1 month. Four carpenters should work on the order in the workshop for 21 working days. Will they be able to deliver the kitchen on time if one of the
- Transferred 81895
The tin body transferred 150,000 J of heat, and its temperature dropped by 10°C. Calculate the mass of the tin body. (c of tin is 0.227 kJ/kg. °C). Enter the resulting weight in grams and round it to two decimal places. - Temperature 81892
By how much °C will the temperature of an iron key weighing 0.004 t change if it receives 360,000 J of heat? ( c of iron is 450 J/kg.°C ) - Temperature 81891
Calculate the mass heat capacity of a steel body weighing 2 kg, which was heated from an initial temperature of 15°C to 80°C by supplying 60 kJ of heat. - Difference 81888
The ropeway climbs at an angle of 22°30'. Calculate its length if the height difference between the lower and upper station is 560m. Sketch a picture - Building 81885
A ladder leans against the building; its length is 7.5 meters. The bottom is 2 meters away from the building. At what height is it leaning against the wall? - Pythagorean 81883
Hello, I have a problem calculating the height on side z in the general triangle XYZ, where z=4 cm, x=1.5 cm, and y=3.7 cm. It was assigned in 8th grade when discussing the Pythagorean theorem. Thank you.
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