Math practice for 13 year olds - page 51 of 433
Number of problems found: 8660
- Minutes 83811
How many minutes is 45% of four hours? - Client
A bank client had €1,320 deposited in her account throughout the year. At the end of the year, €33 in interest was credited to the account. What interest rate was used to determine the principal? - Cheaper skis
In Tesco, skis for 9,000 CZK were reduced by 30 percent, in Makro they were reduced by 20 percent first, and after a week by another 10 percent. Where were the skis cheaper in the end? - Maths exam
One-third of all high school students passed the math exam. Five of these students failed the math exam. One-quarter of all students in the high school graduating class passed the math exam. Calculate how many students there were in the high school gradua - In production
In the production of sea buckthorn liqueur, 1.25 liters of sea buckthorn juice are mixed with 0.75 liters of 4% alcohol. Calculate the percentage of alcohol in sea buckthorn liqueur. Calculate the volume of pure alcohol in liters that is contained in 3 li - Sports Day 2
There are 15 boys in the class. 3 boys and 2 girls did not participate in the sports day. How many girls are there in the class if 80% of the students in the class participated in the sports day? - Tin sheet
How much sheet metal is needed for a triangular prism-shaped box with an edge of 20 cm and a height of 30 cm, the height of the base is 15 cm. An additional 10% of sheet metal is needed for gluing.
- Fair Several students from our class went on excursions. Everyone paid the same amount. In the end, there were a few euros left that needed to be returned to them. If we returned 3 euros to each person, there would still be 5 euros left. If we returned 4 euros
- Infinite speed
A runner runs her first lap of the track at an average speed of 5 km/h. How fast must she run her second lap so that her total average speed is 10 km/h? - Compound fractions
Solve the compound fraction, use the known formulas, and shorten the: (4a²-12a+9)/(4a-6) - Kilogram chleba
We need 750g of flour for one kilogram of bread. How much flour do we need for 20 loaves weighing 1200 g? - Hydraulic lift
Martin needs to lift a 1.5-ton car using a hydraulic device with pistons of sizes 2 cm² and 15 dm². How much force must the device exert on the small piston? - Circumference 83645
The area of a right triangle is 240 cm². Determine its circumference if the given lengths are suspended in a ratio of 5:12. - Groundwater
The groundwater for collecting rainwater has the shape of a prism with trapezoidal bases a=5 m, c=7 m, 4 meters apart. The depth of the tank is 3 meters. How many hectoliters of water can it hold at most if 8% of its volume is taken up by the pump and pip - Similar triangles
We have similar triangles ABC with angle CAB=45° and angle ACB= 30° and a similar triangle OPN. What is the angle NOP in a similar triangle?
- 3 weights
A two-arm lever has a 0.5 kg weight on the left arm at a distance of 64 cm from the axis of rotation and a 0.8 kg weight at a distance of 30 cm from the axis of rotation. How far on the right arm must the 0.7 kg weight be placed for the lever to be in bal - Tightened 83632
The key works like a lever, where one arm is the radius of the bolt, and the other is the length of the key. If key no. 12 (for screws with a diameter of 12 mm) and a length of 12 cm can be tightened with a maximum force of 100 N, what force does the wren - Triangle and Cone
A right triangle has legs 3 cm and 4 cm long. One cone (let's call it A) was created by rotating this triangle around the long leg, and the other (let's call it B) by rotating it around the shorter leg. Which cone has: a) a larger volume b) a smaller surf - Staircase - escalator
A moving staircase moves downwards at a speed of 0.6 m/s. The staircase makes an angle of 45° with the horizontal. A person weighing 80 kg walks upwards at a speed of 0.9 m/s. Determine the distance covered by the person and the work done by him before he - Passenger car and truck
At 6 a.m., a truck left the Factory at 40 km/h. At 6:30, a car drove behind it at 70 km/h. How long, at what time, and how far from the Factory will the passenger car catch up with the truck?
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