Math practice for 13 year olds - page 201 of 413

Number of problems found: 8260

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
Largest wall
Find the area of the largest wall of a prism with a rectangle base with a height of 4 dm, side c = 5 cm, and side b = 6 cm.
Which
Which of the following numbers is the most accurate area of a regular decagon with side s = 2 cm? (A) 9.51 cm² (B) 20 cm² (C) 30.78 cm² (D) 31.84 cm² (E) 32.90 cm²
Pentadecagon
Calculate the area of a regular 15-side polygon inscribed in a circle with a radius r = 4. Express the result to two decimal places.
Rectangle square counting
A rectangle with dimensions of 11 x 13 pieces consists of 11*13 = 143 small identical squares. How many squares, made up of nine small squares, can be drawn in this rectangle (squares can overlap)?
The rectangle
In the rectangle ABCD, the distance of its center from line AB is 3 cm greater than from line BC. The circumference of the rectangle is 52 cm. Calculate the area of the rectangle. Express the result in cm².
Quadrilateral prism
Calculate the surface of a quadrilateral prism according to the input: Area of the diamond base S1 = 2.8 m², length of the base edge a = 14 dm, the prism height 1,500 mm.
Alcohol from potatoes
In the distillery, 10 hl of alcohol can be made from 8 t of potatoes. The rectangular field with 600 m and 200 m dimensions had a yield of 20 t of potatoes per hectare. How many square meters of area are potatoes grown to obtain one liter of alcohol?
Trip with compass
During the trip, Peter went 5 km straight north from the cottage, then 12 km west, and finally returned straight to the cottage. How many kilometers did Peter cover during the whole trip?
Building shadow length
How long a shadow does a 15 m high building cast if a 1-metre-long vertical rod casts a shadow of 90 cm at the same time? Include a sketch showing the similarity.
Cube paper calculation
Calculate how much cm² of paper needs to be bought to make a 60 mm cube if you need to add an extra 12% to the folds.
Diamond area calculation
The ABCD diamond has a circumference of 72 cm. The longer diagonal of the animal with the line segment AB angle is 30 °. Calculate the area of the ABCD diamond.
Can model height
The can of juice is 15 cm high. For advertising purposes, they made a model that can enlarge in a ratio of 5:3. How tall is the advertising?
Motorcycle engine
The motorcycle engine has a constant power of 1.2 kW for 0.5 hours. How much work does the engine do? Express work in kWh and Ws units.
Three examples per-mille
A. Calculate 1.5 ‰ from 4.5 liters of blood. Express the result in milliliters. B. Calculate three ‰ from € 50,000. C. The tray they brought breakfast to the landlord's bed is made of an alloy that contains 830 ‰ of silver. How much silver did they use on

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