Math practice for 13 year olds - page 201 of 415
Number of problems found: 8281
- Square side calculation
Calculate the length of the side of the square if the size of the diagonal u = 9.9 cm is entered. - Number sum difference
The sum of 2 numbers, x, and y, is 80, and their difference is 16. Determine the numbers x and y. - Banknote distribution
We have the amount of 1,250 euros in banknotes of 100 and 50 euros. We have a total of 17 banknotes. How many are there? - 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. - 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 9 m. 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. - 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? - 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? - 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 220 V. 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 in the secondary coil of a transformer that has 1,500 turns, if the primary coil is connected to a voltage of 120 V and has 500 turns? What is the turns ratio, and what type of transformation is it?
- 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 has internal dimensions of 1.6 m × 3.1 m × 1.7 m (width × depth × height) and a payload of 1.7 tonnes. It delivers crates of pastries. Each pastry crate (type 520) has dimensions 600 mm × 400 mm × 200 mm (l × w × h) and a maxim - Flower watering options
Alena, Ivana, Edo, Philip, and Martin came late to school. As a punishment, two will water flowers all over the school after class, and the other three will clean up the classroom. The class teacher couldn't decide who to send to water the flowers, so Geo
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