Math practice for 13 year olds - page 198 of 428
Number of problems found: 8557
- Goat chicken puzzle
There were goats and chickens in the yard. The total number of heads was 15, and the total number of legs was 40. Calculate the number of hens. Every animal has all its legs. - Readers
Readers borrowed 220 books from the library during the first three days. On the second day, readers borrowed half as many books as on the first day and, at the same time, 20 fewer books than on the third day. Depending on the quantity x, express the numbe - The trench
Calculate how many cubic meters of soil need to be removed from the excavation in the shape of an isosceles trapezoid. The top width is 3 meters, the lower width is 1.8 m, the excavation depth is 1 m, and the length is 20 m. - Square and circles
The square in the picture has a side length of a = 20 cm. Circular arcs have centers at the vertices of the square. Calculate the areas of the colored unit. Express area using side a. - Sapling planting calculation
In the forest, there are 84 workers employed in planting saplings. Working 10 hours a day, they would finish the job in 24 days. After 7 days, 14 workers leave. How long will it take the others to finish planting the saplings if they work 12 hours a day f - Pyramid base calculation
The volume of the right 4-side pyramid is 138 m3, and its height is 9m. Calculate the area of the base and the edge of its base. - Cone mesh drawing
Sketch the cone mesh and add the side length, the arc length of the circle, and the circle length to it, if you know: the side length of the cone: s = 51.9 cm cone base circumference = O = 151 mm. - Ointment component ratio
The four-component ointment contains components A, B, C, and D. Components A and B are mixed in a ratio of 1:2, components B and C in a ratio of 3:5, and components B and D in a ratio of 4:3. In what proportion should the pharmacist mix the ointment? - Skirt fabric calculation
They bought fabric to sew a skirt in a tailor's salon. If they sewed skirts 50 cm long, they would sew 70 of them. How many skirts will they sew if they are 70 cm long? - Tractor plowing calculation
Tractor operator Formánek can plow Mr. Kafka's land in 30 hours using a plowing set with a four-blade plow. The tractor driver Divíšek, plowing with a five-blade plow, can plow Kafka's land in 24 hours. In how many hours will the two tractor drivers plow - Cyclist pedestrian pursuit
Behind a pedestrian walking at an average speed of 5 km/h, a cyclist drove from the same place 3 hours later at an average speed of 20 km/h. How long will it take for a cyclist to catch up with a pedestrian? - Toothpaste usage time
The father would use the toothpaste alone for 15 days, the mother for 12 days, and the daughter for ten days. It was used by all three for three days, then only the father and mother. How many days have they used it since the beginning of its use? - Pyramid wall height
How can you calculate the wall height of a pyramid when you know the base edge length is 28 mm and the body height is 42 mm? - Price discount calculation
The original price of the product was 2.55 euros, the price after the discount is 1.99. Find out: a/What % of the original price is the price after the discount b/How much % of the new price is the original price of the product c/o How much % did the prod - Transformer coil turns
The bell uses 8 V alternating voltage obtained from the 220 V mains. The secondary coil of the bell transformer has 60 turns. How many turns must the primary coil have? What is the transformation ratio? - Coils of transformer
The transformer's primary coil has 1100 turns and is connected to a voltage of 220V. How many turns does the secondary coil have when the voltage is 55 V? Find the transformation ratio and decide what kind of transformation. - Coils of transformer What voltage is generated on the secondary coil of the transformer, which has 1500 turns, if the primary coil is connected to a voltage of 120 V and has 500 turns? What is the transformation ratio, and what kind is the transformation?
- Transformer Transformer - U1 = 230 V, N1 = 300, N2 = 1,200, I1 = 4 A. Calculate the secondary coil's transformation ratio, voltage, and current.
- Candy mixture calculation
Clara mixed a mixture of candies of two types: Ham, ham candies at the price of CZK 210 per 1 kg, and Yum, Yum candies at CZK 150 per 1 kg. She mixed the candies so that the mixture of ham, ham, yum, and yum weighed 10 kg, and the price for 1 kg of the mi - Van crate calculation
A Mazda van with a box body with internal dimensions of 1.6 m x 3.1 m x 1.7 m (w x d x h) with a payload of 1.7 tons delivers crates with pastries. Pastry box 520: dimensions 600mm x 400mm x 200mm (l x w x h), load capacity 15 kg. Calculate: a) How many c
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