Math practice for 13 year olds - page 81 of 428
Number of problems found: 8558
- Student grade percentage
There are 32 students in the class; 17 are awarded, 14 passed, and 1 failed. Determine the number percentages of students with honors, successful and not successful students - Cone sphere volume
A sphere is inscribed in an equilateral cone with a base diameter of 12 cm. Calculate the volume of both bodies. What percentage of the volume of the cone is filled by the inscribed sphere? - Men money denarii
Two men talk about how much money each has. The first says to the second: If you give me 12 denarii, we will both have the same. "Second branch: If you give me 12 denarii, I will have ten times more than you. How many denarii did each of them have? - Cylinder diameter height
A cylinder has the same diameter as its height. Calculate these data if the surface is 200 cm square. Report the results to the nearest millimeter. - Girls pocket money Zuzana, Anna, and Eliška receive pocket money every month. They donated part - Zuzana 40%, Anna 50% and Eliška CZK 195. If we add up all 3 amounts and divide the sum by 3, the result will correspond to 4/9 of the pocket money of each of the girls. What is
- Companies 3
Companies supplying electricity to households use two rates. In 1996, the price for 1 kW was 1.10 CZK and night power was sold for 0.46 CZK per kW. In 1997, these rates were 1.28 CZK and 0.53 CZK. Express the ratio of the normal and cheaper rates in both - Airplane distance meeting
Two points are at a distance of 1840 km. An airplane departs from A at 7:00 a.m. and flies at an average speed of 50 km/h faster than another airplane departs from B at 8:00 a.m. At what distance from A do they meet at 9:00? - Salary increase percentage
Since starting the job, Jiri's salary has doubled. By what percentage did his salary increase? - 200 students
200 students sat exams in Czech, mathematics and physics. 114 students passed Czech, 50 students passed mathematics and 41 students passed physics. 14 students passed both Czech and mathematics, 15 students passed both mathematics and physics, and 11 stud - Cone side length
Calculate the length of the side of the cone; they rounded the result to tenths of a millimeter. If you know: radius 24 mm and height 46 mm - Polygon angle ratio
In a certain polygon, the ratio of the sum of the sizes of its internal angles and the sum of the sizes of the complementary angles is 2:5. How many vertices does this polygon have? - Matěj Lojza marbles
Matěj has 2 more marbles than three times the number of marbles that Lojza. Both together have 18 balls. How many marbles does Lojza have? - Triangle angle ratio
In the right-angled triangle ABC (the right angle at vertex C), the angle ratio is α : β = 5 : 3. Calculate the sizes of these angles and convert them to degrees and minutes (e.g., 45°20') - Father son ratio
The father is older than the son by the ratio of 5:2. Dad is older than 33. How old are they both? - Quadrilateral and angles
In a quadrilateral, angle α is twice as large as angle β. Angle γ is 80% of angle α, and angle δ is 30° greater than angle α. Determine the angles of this quadrilateral. - Percentage - fence
We are painting a wooden fence. On the first day, we painted one-half of the fence. The next day, we painted half of the remaining part. On the third day, again, half of the remaining part. After the third painting, we had 12.5 meters of unpainted fence l - Test grade average One of the conditions for classification with grade 2 in geography is to obtain an average of at least 64 points from four tests. The minimum number of points a skater must receive from the fourth test to meet this condition is if she received 59, 67, or
- Apex of the Isosceles triangle
The angle at the apex of an isosceles triangle is 78°. The base is 28.5cm long. What is the shoulder length? - Rectangle perimeter ratio
The sides of the rectangle are relatively 5:4, and the perimeter of the rectangle is 308 dm. Find the area of the rectangle. - Solution mixtures
We have 1 liter of 80% solution. Every hour, pour 1 dl of the solution, add 1 dl of water (a 0% solution), and mix. What percent solution will we have after two mixings?
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