Maths practice for 14 year olds - page 165 of 379
Number of problems found: 7561
- Material 24841
The diameter of the ball screen is 30 cm. If we add 5% of the material to be sewn, how many m² of fabric do we need to make?
- Research in school
For particular research in high school, four pupils are selected from a class of 30 pupils. Calculate the number of all possible results of the selection and further calculate the number of all possible results if it depends on the order in which the stud
- Four-digit numbers
Find four-digit numbers where all the digits are different. For numbers, the sum of the third and fourth digits is twice the sum of the first two digits, and the sum of the first and fourth digits is equal to the sum of the second and third digits. The di
- The circumference
The circumference and width of the rectangle are in a ratio of 5:1. Its area is 216 cm². What is its length?
- Two parallel chords
In a circle 70 cm in diameter, two parallel chords are drawn so that the circle's center lies between the chords. Calculate the distance of these chords if one is 42 cm long and the second is 56 cm long.
- Instrument 24651
Of the 30 students in the class, two-fifths are boys. A quarter of them are learning to play a musical instrument. 6 girls also play it. What percentage of students in this class do not play any musical instrument?
- 14 percent
If 14 percent is 56, what is the base?
- Water percent
A 15 g sample of the substance contains 70% water. After drying, the substance reduced its weight to 9 g. What percentage of water is now in the sample?
- Started
A pedestrian leaves point A with a speed of v1 = 5 km/h. After 3 hours, a cyclist follows him from the same place at a speed of v2 = 20 km/h. But a car starts from point B, 50 km away at the same time as the cyclist. Calculate the distance and time at whi
- The tent
The tent has the shape of a regular square pyramid. The edge of the base is 3 m long, and the tent's height is 2 m. Calculate how much cover (without a floor) is used to make a tent.
- Cylinder in cube
A can in the shape of a cylinder with a height of 10 cm and touching all the walls of the cube is placed into a paper box in the shape of a cube with an edge of 10 cm. What % of the cube's volume can it take up?
- The silver
The silver ring weighs 10 grams. The ring contains 850 per mille of pure silver. Calculate the amount of pure silver in grams.
- Magnified cube
If the lengths of the cube's edges are extended by 5 cm, its volume will increase by 485 cm³. Determine the surface of both the original and the magnified cube.
- Runcated pyramid teapot
The 35 cm high teapot has the shape of a truncated pyramid with the length of the edge of the lower square base a=50 cm and the edges of the rectangular base b: 20 cm and c: 30 cm. How many liters of water will fit in the teapot?
- Probability 24291
Today, one-fifth of 30 students still need to complete a homework assignment. What is the teacher's probability of randomly selecting a pupil with homework during the check?
- Internal angles
In the ABC triangle, the magnitude of the inner angle beta is one-third the magnitude of the angle alpha and 20° larger than the magnitude of the gamma angle. Determine the magnitudes of the interior angles of this triangle.
- Ditch
The excavator dug 40% of the excavation in 2 hours and 20 minutes. How long does it take him to dig the whole ditch?
- Millimeter 24231
Calculate the length of the wall diagonal of a cube with a volume of 7.40 square meters. Express the result to the nearest millimeter.
- Body diagonal
Calculate the surface area, volume, and length of the body diagonal of a cube with an edge length of 4 dm.
- Sooner 24191
If I read a book at a rate of 15 pages a day, I will read it three days sooner than if I read it at a rate of 10 pages a day. If I read at a rate of 6 pages daily, I'll read a book.
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