Math practice for 13 year olds - page 51 of 422

Number of problems found: 8424

Chord 24
A chord with length t = r times the square root of two divides a circle with radius r into two circular segments. What is the ratio of the areas of these segments?
Insulating a house
Five workers are working on insulating a house at such a pace that they could finish the job in 18 days. After three days of work, two workers were called away to another construction site. In how many days will the remaining workers finish the job?
It consumes
A textile machine uses 7/8 meters of fabric to sew shorts. He uses 3/5 meters more fabric to sew a T-shirt. Find out whether 30 meters of fabric will be enough to sew a set of 12 jerseys if one jersey consists of one T-shirt and one pair of shorts.
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
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?

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