Examples for 8th grade - page 48

  1. Coins
    mince_1 On coins found was stated that from the year 87 BC. It is right?
  2. Coffee
    arabica_robusta Coffee merchant has coffee robusta and arabica species. 1 kg Robusta worth 450 CZK, Arabica 1 kg is 300 CZK more expensive. Calculate how many kilograms of Robusta and Arabica will need to produce 30 kg of the mixture so that the mixture cost is 490 CZK p
  3. Container
    canister First day got off 1/4 water from full container, second day 1/5 of the remaining water. How many percent remain container filled?
  4. Two tributaries
    bazen_2 Two tributaries of the pool fill it in 10 hours. One of the tributaries would fill 15 hours. How long would fill the first tributary?
  5. Saw
    kotuc Imagine that the saw blade with diameter 40 cm has one tooth colored with a different color. How long is path describing by the tip of the tooth after 15 minutes, if the blade is rotated 13365 times?
  6. Antennas
    antenas If you give me two antennas will be same. If you give me again your two antenna I have a 5× so many than you. How many antennas have both mans?
  7. Angles
    angles_1 The outer angle of the triangle ABC at the vertex A is 114°12'. The outer angle at the vertex B is 139°18'. What size is the internal angle at the vertex C?
  8. Reciprocal
    inverse It is true (prove it) that if a> b> 0: ?
  9. Train expres
    rjet At 8.00 strarted from Bratislava to Poprad express Tatry. Cities are distant 340 kilometers. At the same time started from Poprad express Danube to Bratislava. Express Tatry's average speed is 80 km/h, Danube 90 km/h. At what distance from Poprad trains w
  10. Otto and Joachim
    monkey_1 Otto and Joachim go through the woods. After some time Otto tire and make 15 minutes stop. Joachim meanwhile continues at 5 km/h. Otto when he set off again, first running speed of 7 km/h, but it keep only 30 sec and 1 minute must continue at 3 km/h. This.
  11. Chimney
    komin_melnik Lower circumference of of the chimney is 12.57 m, top circumference is 5.655 m. The slope of the walls is 87°. Determine the height of the chimney.
  12. Area of the cone
    cone2_1 Calculate the surface area of the cone, you know the base diameter 25 cm and a height 40 cm.
  13. Distance runner
    vltava_run Distance runner already climbed three fifths of the total route. Thus passed 90 km. How many km he have to stop? How long is his route?
  14. Determine the number
    fib2 Determine the number x that ?.
  15. Three piles
    sugar 100 kg of sugar we divide into three piles. The first pile is small. If we added to second 2 kg of sugar it would have 25% more sugar than the first pile. If we added to third pile 3 kg of sugar it would have 20% more sugar than the 2nd pile. How many kil
  16. Rectangles - sides
    rectangles_2 One side of the rectangle is 10 cm longer than second. Shortens longer side by 6 cm and extend shorter by 14 cm increases the area of the rectangle by 130 cm2. What are the dimensions of the original rectangle?
  17. Polygon 42
    12gon Which polygon has 42 more diagonals than sides?
  18. Tangents construct
    tecna Circle is given k (S; 2.5 cm) and an outer line p. Construct a tangent t of the circle that has with a line p angle 60°. How many solutions has the task?
  19. Diplomas
    diploma Suzanne helped write out diplomas. Issuance its first took 3 minutes, each next 2.3 minutes. How much time it will take to write out n=16 diplomas (including the first), write out this pace?
  20. Rectangle
    obdelnik The width of the rectangle is 65% of its length. Perimeter of the rectangle is 132 cm. Determine the dimensions of the rectangle.

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