Math practice for 13 year olds - page 83 of 414
Number of problems found: 8276
- Antifreeze
A car owner needed to replace the antifreeze liquid in the radiator. On the label of the low-freezing liquid it was stated: volume parts of low-freezing liquid 2, volume parts of distilled water 1, freezing point -20°C. How many litres of low-freezing liq - 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
Matthew has 2 more marbles than three times the number of marbles that Louis. Both together have 18 balls. How many marbles does Louis 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 28.5 cm 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? - Toothpaste roll length
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? - Order squares total
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 ... - Observation mean sum
The number of observations is 24, and the value of the mean is 28, then the sum of all the values is ... - Disc angular speed
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 - PIN code probability
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. - Pencil prize count
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? - Butter chocolate price
I paid 36 crowns for butter and chocolate. Butter was CZK 6 more expensive than chocolate. How much did the chocolate cost? - Painter house help
Four painters painted the house in 14 days. How long will it take if 2 more come to help after 5 days? - Rectangle dimension increase
The area of the rectangle is 81.25 cm². If we increase its length by 5 mm, its area increases by 4%. Determine its dimensions.
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