Math practice for 13 year olds - page 78 of 422
Number of problems found: 8424
- 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 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 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? 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. 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? 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? 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 ... 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 ... 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 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. 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? 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? 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? Four painters painted the house in 14 days. How long will it take if 2 more come to help after 5 days?
- Dimensions 81100  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. 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.
- Reduced 81099  A square has a side length of 25 cm. How big is its area if the side is reduced by 25%? A square has a side length of 25 cm. How big is its area if the side is reduced by 25%?
- Quadrilateral 81097  The quadrilateral ABCD is symmetrical about the diagonal AC. The length of AC is 12 cm, the length of BC is 6 cm, and the interior angle at vertex B is right. points E and F are given on the sides AB, and AD so that the triangle ECF is equilateral. Determ The quadrilateral ABCD is symmetrical about the diagonal AC. The length of AC is 12 cm, the length of BC is 6 cm, and the interior angle at vertex B is right. points E and F are given on the sides AB, and AD so that the triangle ECF is equilateral. Determ
- Circumference of edges  The hexagon pyramid has a circumference of 120 cm, and the length of the side edge is 25 cm. Calculate its volume. The hexagon pyramid has a circumference of 120 cm, and the length of the side edge is 25 cm. Calculate its volume.
- Unknown 81081  The number 420 is 20% more than the unknown number. What is the unknown number? The number 420 is 20% more than the unknown number. What is the unknown number?
- Numbers 81079  The ratio of the two numbers is 1:3. Half of the larger one is 135. What is the sum of the two numbers? The ratio of the two numbers is 1:3. Half of the larger one is 135. What is the sum of the two numbers?
- Part-time 81067  I had 350 euros left over from the money I earned from the part-time job. I bought soccer cleats with half of the money I earned and a soccer ball with the other half. How much did I earn from the part-time job? I had 350 euros left over from the money I earned from the part-time job. I bought soccer cleats with half of the money I earned and a soccer ball with the other half. How much did I earn from the part-time job?
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