Math practice for 13 year olds - page 339 of 424

Number of problems found: 8472

Rectangle from string
String 12 m. Make a rectangle when one side is two times longer than its width.
Tree mesh
The farm provided around 150 fruit trees with a trunk diameter of 2 dm with mesh to protect them from wild animals. The mesh was placed so that it was 9 cm away from the trunk. How many regular meters of mesh were needed?
Three dice
What is the probability that when we roll three dice, we roll the number 1,2,3?
Pyramid 4sides
Calculate the volume and the surface of a regular quadrilateral pyramid when the edge of the base is 4 cm long, and the pyramid's height is 7 cm.
Sputnik
The first Earth satellite was flying at a speed of 8000 m/s. At that rate, he circled the Earth in 82 minutes. Jet flies at an average speed of 800 km/h. How long would it take to circle the Earth around?
Roof 8
How many liters of air is under the tower's roof, which has the shape of a regular six-sided pyramid with a 3,6-meter-long bottom edge and a 2,5-meter height? Calculate the supporting columns occupy about 7% of the volume under the roof.
Vase capacity
The cylindrical vase is 28 cm high. Its inner diameter d = 1.1 dm. How many liters of water will fit in it if the bottom thickness is 1.5 cm?
Water height
The cylindrical container with a diameter of 1.8 m contains 2000 l of water. What height does the water reach?
Rotating cone
Calculate the volume and the surface area of a rotating cone of base radius r = 2.3 dm and a height h = 46 mm.
Cube diagonals
If you know the length of the body diagonal u = 216 cm, determine the cube's volume and surface area.
Algebrogram
Solve cryptarithmetic (alphametics) for a sum of three numbers: BEK KEMR SOMR ________ HERCI
Cake dough
The kneaded cake dough has a volume of 1.8 l. When baking, it increases in volume by about two-thirds. Can it fit on a baking sheet measuring 36 × 30 × 8 cm? How tall will the cake be after baking?
Pyramid
The pyramid has a base rectangle with a = 6 cm and b = 8 cm. The side edges are the same, and their length is 12.5 cm. Calculate the surface of the pyramid.
Two numbers
The sum of the two numbers is 75. Find these numbers. Three-quarters of the first are one-seventh of the second.
Hectoliters in a tank
The block tank held 288 hectoliters of water. The bottom dimensions are 12m and 6m, and the depth is 2m. What percent of the tank volume does the water occupy?
Larger number
Which number a is 15 smaller (solve also for a is larger) than its half?
Hexagonal prism height
A container has the shape of a regular hexagonal prism with a base and a capacity of 0.5 dm², which means three quarter-liter cups of water fill the brim. What is the height of a container?
Cuboid and ratio
A cuboid has dimensions in a ratio of 1:2:6, and the surface area of the cuboid is 1000 dm². Calculate the volume of the cuboid.
The road
The road roller has a diameter of 1.2 m and a width of 180 cm. How many m² of the road does it level when it turns 35 times?
Folded square
ABCD is a square. The square is folded on the midpoint of AB, and A is folded onto the fold, creating a shaded region. The perimeter of the shaded figure is 75. Find the area of square ABCD

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