Maths practice for 14 year olds - page 288 of 361
Number of problems found: 7215
- Hexagonal prism 2
The regular hexagonal prism has a surface of 140 cm² and a height of 5 cm. Calculate its volume. - Circle election
How many different ways can members of a 7-member philatelic circle elect a secretary and a steward from among themselves? - PIN attempts
How many attempts do I need to guess the 3-digit PIN to be sure I can guess it? - Two-digit numbers
Write all the two-digit numbers that can be composed of the digit 7,8,9 without repeating the digits. Which ones are divisible b) two, c) three d) six? - Original reduce
If we reduce the unknown number by 469, we get 65% of the original number. What is the original number? - Product equals sum
The product of two numbers equals their sum. One number is four times the other. Find these numbers, given that neither equals zero. - Well digging cost
The width of the well with the masonry should be 1.8 m. How much will digging a well 16 m deep be paid if an average of 800 CZK is paid from meter cubic? - The tent
The tent shape of a regular quadrilateral pyramid has a base edge length of a = 2 m and a height of v = 1.8 m. If we have to add 7% of the seams, how many m² of cloth did we need to make the tent? How many m³ of air will be in the tent? - Cube walls
Find the volume and surface area of the cube if the area of one wall is 40 cm². - Quadrangular prism
The regular quadrilateral prism has a base edge of 7.1 cm and a side edge of 18.2 cm long. Calculate its volume and surface area. - Rotary bodies
The rotating cone and the rotary cylinder have the same volume of 180 cm³ and the same height, v = 15 cm. Which of these two bodies has a larger surface area? - Five pumps
Three same pumps fill the tank with 50400 liters of diesel in 7 hours. How many liters of diesel will it take in 4 hours if we add two more of the same pumps and pump them the same way? How much more (or less) will they get if we add 2 of the same pumps a - Copper wire
What is the weight of 1000 m copper wire with a diameter of 5 mm when metric density p = 8.8 g/cm³? - The gardener
The gardener bought trees for 960 CZK. If every tree were cheaper by 12 CZK, he would have gotten four more trees for the same money. How many trees did he buy? - Aquarium depth
The aquarium has the shape of a block with a length of 0.7 m and a width of 25 cm. It can hold 56 liters of water. How deep is the aquarium? - Pyramid four sides
A regular tetrahedral pyramid has a body height of 38 cm and a wall height of 42 cm. Calculate the surface area of the pyramid; the result is round to square centimeters. - RT perimeter
The leg of the rectangular triangle is 7 cm shorter than the second leg and 8 cm shorter than the hypotenuse. Calculate the triangle circumference. - Trapezium area
Given is a trapezoid ABCD with bases AB, CD. Let K be side AB's midpoint, and point L be side CD's midpoint. The area of triangle ALB is 15 cm2, and the area of triangle DKC is 10 cm². Calculate the area of trapezium ABCD. - Row strings
Find how many strings there are in the first row if there are 44 strings in the eighth row, and in each subsequent row, there are five more strings than in the previous row. - Sphere vs cube
How much % of the surface of a sphere of radius 12 cm is the surface of a cube inscribed in this sphere?
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