Maths practice for 14 year olds - page 132 of 362

Number of problems found: 7235

Two cables
On a flat plain, two columns are erected vertically upwards. One is 7 m high, and the other 4 m. Cables are stretched between the top of one column and the foot of the other column. At what height will the cables cross? Assume that the cables do not sag.
Pyramid stone weight
The largest Egyptian pyramid has the shape of a regular four-sided pyramid with a base edge of approximately 227 meters and a height of about 140 meters. How many tons of stone did the workers transport to build it? One cube of stone weighs 2500 kg and ne
Plot dimension increase
The surface area of the rectangular plot needs to be increased by 33.7 percent. One dimension was extended by 2.9 percent. By what percentage should the second dimension be increased? Round the result to two decimal places.
Fireplace power consumption
A current of 20 A passes through the heating spiral of the electric fireplace with a resistance of 10 Ω for 2.5 hours. Determine the power input of the fireplace and the consumed electrical energy
Bulb voltage current
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?
Bulb resistance
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 electricity bill. To the nearest tenth of a percent, what percentage of Ramon's earnings is 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).
Exam average
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
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:

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