Math practice for 13 year olds - page 78 of 434
Number of problems found: 8665
- Percentage 81198
Since starting the job, Jiri's salary has doubled. By what percentage did his salary increase? - Millimeter 81160
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 - Complementary 81152
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? - Together 81151
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? - Right-angled 81150
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 81149
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 - Classification 81133
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? - Relatively 81129
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? - Toothpaste 81127
How long will the roll of toothpaste be extruded from the tube if the volume of the toothpaste is 100 ml and the diameter of the opening is 8 mm? - Processed 81125
The total number of orders processed in the courier office in five days is 10, 6, 8, 7, 9, then the total of Squares is ... - Observations 81124
The number of observations is 24, and the value of the mean is 28, then the sum of all the values is ...
- Revolutions 81118
1. A disc makes 15 revolutions per minute. Determine his angular speed and the boy's speed on the seat that describes a circle with a radius of 5 m. 2. The grinding wheel rotates at 600 revolutions per minute. Determine the period and angular velocity. Th - Probability 81117
Martin forgot the 4-digit PIN, and he remembered the first three numbers. The fourth number is odd. What is the probability in % that he will be able to determine the PIN? He has only one attempt. - Twenty-five 81116
Twenty-five pencils were bought as prizes in the school competition. The more expensive pencils were for 20 CZK, the cheaper ones for 15 CZK. The entire amount paid was 455 CZK. How many are there? - Chocolate 81103
I paid 36 crowns for butter and chocolate. Butter was CZK 6 more expensive than chocolate. How much did the chocolate cost? - Painters 81101
Four painters painted the house in 14 days. How long will it take if 2 more come to help after 5 days?
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