Examples for 8th grade - page 18

  1. Cone and the ratio
    kuzel Rotational cone has a height 23 cm and the ratio of the base surface to lateral surface is 7: 9. Calculate a surface of the base and the lateral surface.
  2. EQL triangle
    rs_triangle Calculate inradius and circumradius of equilateral triangle with side a=77 cm.
  3. Sector
    vysec The perimeter of a circular sector with an angle 1.8 rad is 64 cm. Determine the radius of the circle from which the sector comes.
  4. Scrap
    chair_bad From 6 products are 3 scrap. What is the probability that the random pick of 2 products have no defective product?
  5. Sphere A2V
    sphere3 Surface of the sphere is 241 mm2. What is its volume?
  6. Truck
    truck Truck went for 4 hours and 48 minutes. If truck increase speed by 21 km/h, went same distance in 1.8 hours. Calculate this distance.
  7. Cube wall
    kocka Surface of first cube wall his 225 mm2. Second cube area is 60% of the surface of the first cube. Determine the length of the edge of the second cube (x).
  8. Block
    brick_lego Calculate the volume of a cuboid ABCDEFGH if |AB| = 16 cm, |BC| = 19 cm and the angle ∠CDG = 36.9°
  9. Water inlets
    pipe Inlet valve with a flow rate of 12 liters per second is filled tank for 72 minutes. How long take to fill full tank if we open one more such valve half an hour after?
  10. Triangle angles
    triangles_2 The angles α, β, γ in triangle ABC are in the ratio 6:2:6. Calculate size of angles.
  11. Steamship
    parnik Between the two ports on the river is going steamship. The journey there and back takes 8:42. Downstream steamship traveling at 20 km/h, upstream 9 km/h. What is the distance between the ports?
  12. Three workers
    three_workers Three workers A, B, C have to work on a specific task. Workers A and B completed whole task in 11 days, B together with C for 15 days, A together with C for 24 days. How long it would take to complete the task every one of them alone? How long it would.
  13. Leveling
    quattro Calculate how many 25 kg bags of leveling concrete must be purchased if we leveling room 15 m2 to the "height" 6 mm if consumtion is 1.5 kg per square meter and millimeter thickness.
  14. Blueberries
    boruvky Marie earns 3 liters of blueberries for 3.4 hours, Peter 2.4 liters for 2.9 hours. How long have earns together one liter?
  15. Heron backlaw
    heron_math Calculate missing side in a triangle with sides 17 and 34 and area 275.
  16. XY triangle
    triangle Determine area of triangle given by line 7x+8y-69=0 and coordinate axes x and y.
  17. Wheat
    field_1 The rectangle shaped field with dimensions 889 m and 1336 m harvested last year was 6235 q wheat. (1 q = 1 quintal = 100 kg). During the year, it was necessary to fix the pipe and therefore did kick wide 3 m parallel to the side of the field 1336 m, where.
  18. Christmas Day
    stedryd In leap years was 53 Sundays. On what day of the week fell to Christmas Day?
  19. Coin and die
    die Flip a coin and then roll a six-sided die. How many possible combinations are there?
  20. Shooter
    terc_1 The shooter fired to a target from distance 11 m The individual concentric circle of targets have a radius increments 1 cm (25 points) by 1 point. Shot was shifted by 8'(angle degree minutes). How many points should win his shot?

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