Examples for 8th grade - page 11

  1. Equilateral triangle
    3angle_in_circle How long should be the minimum radius of the circular plate to be cut equilateral triangle with side 7 mm from it?
  2. Garden
    garden_2 Father dig up the garden in 9 hours. Son in 13 hours. How many hours take dig up the garden together?
  3. Bicycle wheel
    bicycle Bicycle wheel has a diameter of 70 cm. Approximately how many times the wheel rotates at 4.7 km long trip?
  4. Number ratio
    ratio2 Calculate two positive numbers that its ratio is 6:6 and difference was 0.
  5. Cube
    kocka_rubik The cube weighs 24 kg. How weight is cube of the same material, if its dimensions are 2-times smaller?
  6. Hexagon A
    hexagon Calculate area of regular hexagon inscribed in circle with radius r=9 cm.
  7. Rhombus 2
    koso Calculate the area of rhombus which has a height v=48 mm and shorter diagonal u = 60 mm long.
  8. Similarity coefficient
    eqlateral_triangles The ratio of similarity of two equilateral triangles is 3.5 (ie 7:2). The length of the side of smaller triangle is 2.4 cm. Calculate the perimeter and area of ​​the larger triangle.
  9. Balls
    steel_ball Three metal balls with volumes V1=71 cm3 V2=78 cm3 and V3=64 cm3 melted into one ball. Determine it's surface area.
  10. Team
    football The football team has 11 players. Their average age is 20 years. During the match due to injury, one player withdraws and the average age of the team is 18. How old was injured player?
  11. Road
    cesta Between cities A and B is route 7 km long of fall average 4‰. Calculate the height difference of cities A and B.
  12. Shelf
    bookshelf.JPG How many ways are there to arrange 6 books on a shelf?
  13. Right isosceles
    right_isosceles_triangle Calculate area of the isosceles right triangle which perimeter is 49 cm.
  14. Speed of Slovakian trains
    zssk_train Rudolf decided to take the train from the station 'Trnava' to 'Zemianske Kostoľany'. In the train timetables found train R 725 Remata : km0Bratislava hl.st.12:574Bratislava-Vinohrady13:0113:0219Pezinok13:1213:1346Trnava13:3013:3263Leopoldov13:4514:0168H
  15. Diofant 2
    1diofantos Is equation ? solvable on the set of integers Z?
  16. Hole
    cube_w_hole In the center of the cube with edge 14 cm we will drill cylinder shape hole. Volume of the hole must be 27% of the cube. What drill diameter should be chosen?
  17. Air
    air_room_people Room is 40.1 m long, 25.2 dm wide and 369 cm high. How many people can simultaneously be in this room if for hygiene reasons is calculated 5100 dm3 of air per person?
  18. Tinsmith
    rury Tinsmith construct chimney pipe 145 cm long and 15 cm wide. What are the dimensions of the sheet will have to prepare for the construction of a pipe when the plate overlap at the joint add $x cm width of the plate?
  19. Radius
    green_circle Determine the radius of the circle, if its perimeter and area is the same number.
  20. Parquet floor
    Parkett Three workers laid parquet floor for 2.9 hour. The first one would do this work alone 9 hours, the second in 7 hours. For how many hours would fulfill this work the third worker, if he worked alone?

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