Math practice for 13 year olds - page 165 of 413
Number of problems found: 8260
- Heat transfer
We placed a lead object weighing 0.4 kg and 250 °C in 0.4 L water. What was the initial temperature of water t2 if the object's temperature and the water after reaching equilibrium was 35 °C? We assume that the heat exchange occurred only between the lead - Number summand division
Express 68 as the sum of two different positive integers. If you divide the larger by the smaller, do you get exactly 3? - Fertilizer
I have 4 liters of 10% fertilizer. How much water must I add to have a 2% solution? - Pyramid surface height
The regular quadrilateral pyramid has a volume of 212 m³ and a base edge a = 7.2 m. Calculate the surface area and height of the pyramid. - Pyramid plasticine The base of the needle is a rectangle with dimensions of 20 cm and 10 cm, its height is 15 cm. Will the plasticine we needed to model this pyramid be enough to model two pyramids with a square base of 10 x 10 cm and a height of 15 cm?
- Cone surface volume
Calculate the surface and volume of the cone if you know that the base radius r = 5 dm and the side length s = 7 dm. - Dress discount price
The dress initially cost € 30 and was 20% cheaper on sale. What is the new price of the dress? The latest price is: - Tower roof
The tower's roof is a cone with a base diameter of 12 m and a height of 8 m. At least how many square meters of roofing are needed to cover it? - Three
Three pavers will pave the sidewalk in 4 days. How long does it take for two tiles to pave the same sidewalk? - Quadrilateral pyramid
The regular quadrilateral pyramid has a surface of 260 cm² and a side wall area of 40 cm². Calculate the length of the base edge and the wall height. - Aircraft
From the aircraft flying at an altitude of 500 m, they observed places A and B (at the same altitude) in the direction of flight at depth angles alpha = 48° and beta = 35°. What is the distance between places A and B? - A semi-circular
A semi-circular fishbowl is filled with water and has a diameter of 10 feet. What is the total water weight to the nearest pound in the tank if water weighs 62.5 pounds per cubic foot? - Carpenter chair
Eight carpenters will make 30 chairs in 2 days. In how many days will ten carpenters make 72 chairs? - Plan scale
On mill paper, the dimensions are 11 * 7.5 mm, and the external dimensions of the sauna are 4.4 * 3 m. On what scale is the plan drawn on graph paper? - Truck concrete
Ten identical trucks will take 240 tons of concrete to build the dam in 3 working days. How many tons of concrete will seven trucks take to make the dam in 5 days? - Number ratio division
Divide the number 20 into two parts so that the first part is four times larger than the second. What is the ratio? - Beginners - skiing
Out of 150 children in a ski course, 40 were beginners. What percentage is that? - Deceleration
In a braking test, a vehicle that travels at 51 km/h stops in 5 s. What is its acceleration? - Circle distance
For circles k1 (S1, 4 cm) and k2 (S2, 3 cm) and it holds that | S1S2 | = 8 cm. Determine the distance between the circles K1 and K2. - Brother age
Jacob is ten years younger than his brother Martin. He is a total of 24 years old. How old is Jacob?
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