Examples for 8th grade - page 16

  1. Tanker
    oil-tanker An oil tanker can be emptied by the first pump in 4.4 hours. Second pump can empty an tanker in 7.8 hours. If the first pump started at 8:00 and second 1.4 hour later, at what time will the tanker be empty?
  2. Unknown x
    UnknownX If we add to unknown number 72, then divide by 2 and then subtract 29, we get back an unknown number. What is this unknown number?
  3. Perimeter and legs
    RT_triangle Determine the perimeter of a right triangle if the length of one leg is 75% length of the second leg and its content area is 24 cm2.
  4. Accidents
    nehoda-pomnik The count of accidents in 1993 caused 8009 women which is 7.1%. How many men caused the accidents?
  5. Pentagon
    5gon_1 Within a regular pentagon ABCDE point P is such that the triangle is equilateral ABP. How big is the angle BCP? Make a sketch.
  6. Jewel
    rhombus3 Rhombus-shaped jewel have area of 86 mm2 and the edge in long 10 mm. Calculate the size of rhombus acute angle.
  7. Block
    brick_lego Calculate the volume of a cuboid ABCDEFGH if |AB| = 11 cm, |BC| = 8 cm and the angle ∠CDG = 29.4°
  8. EQL triangle
    rs_triangle Calculate inradius and circumradius of equilateral triangle with side a=100 cm.
  9. Parallelogram
    paralleogram Calculate area of the parallelogram ABCD as shown if |AB| = 45 cm, |BC| = 23 cm and angle BAD = 30°
  10. Right triangle
    right_triangles Calculate the missing side b and interior angles, perimeter and area of ​​a right triangle if a=10 cm and hypotenuse c = 16 cm.
  11. Sphere A2V
    sphere3 Surface of the sphere is 306 m2. What is its volume?
  12. Cone and the ratio
    kuzel Rotational cone has a height 28 cm and the ratio of the base surface to lateral surface is 4: 7. Calculate a surface of the base and the lateral surface.
  13. Wiring
    install_pipes Conduit has a cross section 492 mm. Maybe put it into 5 conductors with a cross section S2 $mm2?
  14. Heron backlaw
    heron_math Calculate missing side in a triangle with sides 33 and 27 and area 118.3.
  15. Wheat
    field_1 The rectangle shaped field with dimensions 979 m and 540 m harvested last year was 2775 q wheat. (1 q = 1 quintal = 100 kg). During the year, it was necessary to fix the pipe and therefore did kick wide 6 m parallel to the side of the field 540 m, where no
  16. Steamship
    parnik Between the two ports on the river is going steamship. The journey there and back takes 14:49. Downstream steamship traveling at 21 km/h, upstream 9 km/h. What is the distance between the ports?
  17. Triangular pyramid
    tetrahedron1 Calculate the volume and surface area of a regular triangular pyramid whose height is equal to the length of the base edges 10 cm.
  18. Cardboard box
    krabicka We want to make a cardboard box shaped quadrangular prism with rhombic base. Rhombus has a side of 5 cm and 8 cm one diagonal long. The height of the box to be 12 cm. The box will be open at the top. How many square centimeters cardboard we need, if we cal
  19. Blueberries
    boruvky Marie earns 1.8 liters of blueberries for 1.2 hours, Peter 2.6 liters for 1.2 hours. How long have earns together one liter?
  20. Leveling
    quattro Calculate how many 25 kg bags of leveling concrete must be purchased if we leveling room 28 m2 to the "height" 12 mm if consumtion is 1.7 kg per square meter and millimeter thickness.

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