Examples for 8th grade - page 40

  1. RT 11
    right_triangle Calculate the area of right tirangle if its perimeter is p = 46 m and one cathethus is 18 m long.
  2. CD disc
    CD_disc A compact disc has a diameter of 11.8 cm. What is the surface area of the disc in square centimeters?
  3. Diameter
    diameter_circle If the endpoints of a diameter of a circle are A(10, -5) and B (8, 7), what is the radius of the circle?
  4. Carpenter
    tesari From wooden block carpenter cut off a small cuboid block with half the edge length. How many percent of wood he cut off?
  5. Racer
    car_championship The first racer run at a speed 12 m/s and is 470 meters before the finish and ahead 22 meters before second competitor. At what speed must run the second racer to catch first racer at the finish line?
  6. Plastic pipe
    pvc-trubka Calculate weight of the plastic pipe with diameter d = 60 mm and length 400 cm if the wall thickness is 6 mm and the density of plastic is 1228 kg/m3.
  7. Task
    cube_1 I have homework. The cube has an edge 11 cm long and I must find wall and body diagonal.
  8. Rhombus and inscribed
    rhombus_2 Rhombus has side a = 72 cm, the radius of the inscribed circle is r = 10 cm. Calculate the length of its two diagonals.
  9. Angles
    rhombus_1 Determine the interior angles of a rhombus with area 240.6 cm2 and perimeter 64 cm.
  10. Acids
    acids 76% acid was make from same acid of two different concentrations. Amount weaker acid to the stronger acid is in ratio 2:1. What was the concentration of the weaker acid, if stronger had 94% concentration?
  11. Motion
    bus_1 From two different locations distant 104 km started against car and bus. The car started at 5:30 with average speed 58 km/h. Bus started at 6:40 with average speed 79 km/h. When they meet? How many kilometers went the bus?
  12. Rotation
    cone_1 Right triangle with legs 9 cm and 16 cm rotate around longer leg. Calculate the volume and surface area of the formed cone.
  13. Numbers
    ten Determine the number of all positive integers less than 2937474 if each is divisible by 11, 23, 17. What is its sum?
  14. Tinsmith
    rury Tinsmith construct chimney pipe 126 cm long and 11 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?
  15. Rates
    gas_meter When gas consumption, the consumer may choose one of two rates: rate A - which pays 0.35 € per 1 m3 of gas a flat monthly fee of 3.6 € (regardless of consumption) rate B - which pays 0.295 € per 1 m3 of gas a flat monthly fee of 8.3 € From what monthl
  16. Two friends
    beers Two friends met as a good man perish together for a beer. After recovery the most important topics (politics, women, football ...), one asks: - And how many do you have children? - I have 3 children. - And how many years have? Friend already not want to an
  17. Apples
    jablka_4 Apples I picked 600 kg this year. Autumn's apples was 4 times more than the summer. How many kg's I picked the summer and how much winter apples?
  18. Rings groups
    venn 27 pupils attend some group; dance group attends 14 pupils, 21 pupils sporty group and dramatic group 16 pupils. Dance and sporting attend 9 pupils, dance and drama 6 pupil, sporty and dramatic 11 pupils. How many pupils attend all three groups?
  19. Dried apples
    jablka_2 How many kilograms of fresh apples id needed to 120 kg of dried apples when from 0.4 tons of fresh apples we get 75 kg of dried apples?
  20. Interst on savings
    ecb_2 The bank offers 1.6% interest. How many euros have to insert at the beginning if we received € 15 on the interest?

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