Maths practice for 14 year olds - page 129 of 376
Number of problems found: 7502
- 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 o - Number summand division
Express the number 68 as this property's sum of two different summands. If you divide a larger sum by a smaller sum, will you receive a result of 3? - Fertilizer
I have 4 liters of 10% fertilizer. How much water must I add to have a 2% solution? - 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? - Tower's view
From the church tower's view at 65 m, the top of the house can be seen at a depth angle of alpha = 45° and its bottom at a depth angle of beta = 58°. Calculate the house's height and its distance from the church. - Aircraft
From the aircraft flying at an altitude of 500m, 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? - Acid mixture
How many grams of 70% and 45% acid must be mixed to form 300 grams of 60% acid? - 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? - Iodine solution preparation
Calculate how many grams of iodine and ethanol are needed to prepare 200 grams of 6% iodine in ethanol solution. - Measurement - the laboratory
Laboratory measurements determined the following roller lengths (in millimeters): {402; 410; 412; 410; 413; 418; 405; 409; 410; 409} Calculate arithmetic, geometric mean, mode, and median. - 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? - 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? - Brother age
Jakub is ten years younger than his brother Martin. He is a total of 24 years old. How old is Jakub? - Roof material
How many square meters of roofing is needed to cover the cone-shaped roof if the perimeter of its base is 15.7m and a height of 30dm
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