Math practice for 13 year olds - page 81 of 422

Number of problems found: 8423

Motorcyclist 80762
A motorcycle travels at a speed of 116 km/h, and a truck at a speed of 88 km/h. At what time will the motorcyclist reach the truck if, at 7:00 AM, the truck is ahead of him by 56 km?
Parallelogram 80761
Construct a parallelogram ABCD if a=5 cm, height to side a is 5 cm, and angle ASB = 120 degrees. S is the intersection of the diagonals.
Right-angled 80745
The area of a right-angled triangle KLM with a right angle at the vertex L is 60 mm square, and its hypotenuse k is 10 mm long. Triangles KLM and RST are similar. The similarity ratio is k=2.5. Calculate the area of triangle RST.
Organization 80743
The apprentice came to his master with an improvement proposal, and with better work organization, we will reduce costs by 45% this year, 30% next year, and 25% the following year. The production won't cost us anything. Has the apprentice received a rewar
Similarity 80742
Calculate the perimeter of triangle ABC if you know that it is similar to triangle EFG in which e=144 mm, f=164 mm, g=92 mm, and the similarity ratio is 4. Express the result in cm.
Calculate 80741
In the camp, the children made a mock-up of the campsite. In its center was a maple, which had a height of 28 cm on the model. Calculate the height of the maple in the campsite if, in the morning, it casts a shadow 14 m long and its model has a shadow 49
Cylinder 80733
How tall is a cylinder whose shell has a volume equal to the base? What is the volume of this cylinder?
Quadrilateral 80729
Quadrilateral ABCD has side lengths AB=13cm, CD=3cm, AD=4cm. Angles ACB and ADC are right angles. Calculate the perimeter of quadrilateral ABCD.
Fifty-meter 80722
Calculate how many hectoliters of water can fit in a fifty-meter sloped pool; if the smallest depth is 1.2 m and the largest depth is 3 m, the width of the pool is 20 m.
Percentage 80721
Calculate what percentage is €37 from €49.
Cube-shaped 80720
Pavel has a cube-shaped aquarium with a volume of 240 liters. Thomas has an aquarium whose all dimensions are half the dimensions of Paul's aquarium. What is the volume of Thomas's aquarium?
Hibernation 80718
The bear weighed 410 kg at the beginning of winter and lost 10 percent during hibernation. He gained 10 percent of his weight from spring to fall. Find out if the bear's weight was greater at the beginning of winter or autumn by what percentage.
Effectiveness 80711
When testing the effectiveness of an electric cooker with data of 220 V, 1200 W, 1 kg of water at a temperature of 15 degrees Celsius was boiled for 8.5 minutes. Calculate the stove efficiency corresponding to these data
Percentage 80710
Calculate what percentage is 12€ of 60€.
Resistances 80706
The current I = 4A branches into three wires with resistances R1 = 2Ώ, R2 = 5Ώ, R3 = 10Ώ. Calculate the total resistance of the connection and the voltage of the source. How big are the currents in each wire?
Current in the bulb
The bulb is rated 6 V, 0.2 A. Determine the current rating of the bulb.
Automatically 80704
The electric circuit breaker automatically switches off the circuit of the 220 V electrical network at a current of 6 A. Determine the maximum power in the protected circuit.
Resistance 80703
An immersion cooker has a resistance of 30 ohms and is connected to a voltage of 120 V. How much heat is generated in 2 hours?
Consumption 80702
A current of 500 mA passed through the filament of a light bulb with a resistance of 400 ohms. What is the consumption of a light bulb in 5 hours?
Resistance 80699
The immersion cooker plate has data 220 V, 300 W. What is the resistance of the heating wire?

Do you have unsolved math question and you need help? Ask a question, and we will try to solve it. We solve math question.