Math practice for 13 year olds - page 51 of 434
Number of problems found: 8668
- Repeatition not allowed
How many four-digit numbers can be formed from the numbers 3 5 8 9 if they are not allowed to be repeated? - Kilometers of the journey
A cyclist traveled 199 km in three days. On the first day, he traveled four times more than on the second day and on the second day, he traveled 7 km less than on the third day. How many kilometers did he travel each day? - Plums - a quarter
How many plums were originally on the bowl if Iva ate a quarter, Jana a fifth, Mišo three-eighths, and then there were 7 left? - 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
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