Maths practice for 14 year olds - page 124 of 370
Number of problems found: 7393
- Electrical 44931
A current of 20 A passes through the heating spiral of the electric fireplace with a resistance of 10Ω for 2.5 hours. Determine the power input of the fireplace and the consumed electrical energy - Resistance 44921
The bulb's resistance at a power input of 40 W is 10 Ω. To what voltage source is it connected? How much current is flowing through it? - Resistance 44911 Determine the resistance of a bulb whose wattage at a source voltage of 220 V is 15 W.
- A number 4
A number is made up of two digits. The sum of the digits is 11. if the digits are interchanged, the original number increases by 9. Find the original number - Ramon
Ramon earns 1,810 each month and pays a 53.20 bill on electricity. To the nearest tenth of a percent, what percent of Ramon's earnings are spent on electricity each month? - The roof
The house's roof has the shape of a regular quadrilateral pyramid 5 m high and the edge of the base 7 m. How many tiles with an area of 540 cm² are needed? - Cathedral roof sphere
Cathedral height is 110 m, sphere weight 6000 kg, dome diameter 43 m, crane arm length 25 m a) what was the diameter of this sphere? b) how much mechanical work had to be done to lift it to the designated place? - Transmission of electricity
The electric field performs work 1610 J in the transmission of electric charge of 7 Coulombs between the heating coil terminals. Calculate the voltage between the terminals. - Milk cream
How many percent of whipped cream do we make if we mix 41 liters of 38.8% whipped cream and 9 liters of 3.8% milk? (Percent means a percentage of milk fat). - Remaining 44651
Jane has to pass ten exams in a year. So far, she has made six and has an average of 2.5. What average must she reach from the remaining tests for her overall average for the year to be 2? - 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 - Different 44621
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? - Dimensions 44551
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? - Calculate 44541
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. - Initially 44521
The dress initially cost € 30 and was 20% cheaper on sale. What is the new price of the dress? The latest price is: - Diameter 44511
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? - Grams 44441
How many grams of 70% and 45% acid must be mixed to form 300 grams of 60% acid?
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