Examples for 8th grade - page 99

  1. Water tank
    nadrz_13 A 288 hectoliter of water was poured into the tank with dimensions 12 m and 6 m bottom and 2 m depth. What part of the volume of the tank water occupied? Calculate the surface of tank wetted with water.
  2. Together 3
    painter_8 If Sally can paint a house in 4 hours, and John can paint the same house in 6 hours, how long will it take for both of them to paint the house together?
  3. Orchard
    jablone_8 One-eighth of the trees in the fruit plant in winter froze and one-twelfth of damaged disease and pests. Healthy trees remained 152. Is it enough to supply 35 trees to restore the original number of trees in the orchard?
  4. Exponential equation
    exp_8 Determine the value of having y in the expression (3^y): (4^-1)=36.Y is a natural number greater than zero.
  5. Electric energy
    bulb _3 There are 875 identical light bulbs in the sports hall lighting for 2 hours. How long does the same amount of electricity consume 100 such bulbs?
  6. Seamstress
    textiles_2 The seamstress cut the fabric into 3 parts. The first part was the eighth fabric, the second part was three-fifths of the fabric and the third part had a length of 66 cm. Calculate the original length of the fabric.
  7. Peroxide
    chemia_3 How many ml 30% of peroxide (H2O2) should be poured into 100ml H2O to give a 20% solution?
  8. Find radius
    numbers_49 Find radius of circle using pythagorean theorem where a=9, b=r, c= 6+r
  9. Sale discount
    penize_49 The product was discounted so that eight products at a new price cost just as five products at an old price. How many percents is the new price lower than the old price?
  10. Construct
    kosodlznik3 Construct a rhombus ABCD, if the size of the diagonal AC is 6 cm and diagonal BD 8 cm long.
  11. The pole
    tlf_pillar The telegraph pole is supported by a 4 m bullet at 3/4 of its height, the end of which is at a distance 2.5 m from the pole post. Calculate the height of the telegraph pole.
  12. Our house
    malovka_6 Our house would paint four painters in 14 days. How long could it paint five painters? How long will it take if two other painters will come to help after 5 days?
  13. MO Z8–I–6 2018
    lich_1 In the KLMN trapeze, KL has a 40 cm base and an MN of 16 cm. Point P lies on the KL line so that the NP segment divides the trapezoid into two parts with the same area. Find the length of the KP line.
  14. Butter
    factory_butter At the Orville redenbocher popcorn factory there is a tank of artificial butter substitute which is 55 feet tall and 18 feet in diameter. How many gallons of artificial butter substitute can the tank contain?
  15. Shadow
    shadow_1 A meter pole perpendicular to the ground throws a shadow of 40 cm long, the house throws a shadow 6 meters long. What is the height of the house?
  16. Bicycle gear
    bicycle_gears The pedal bicycle wheel has 56 teeth and a rear 20 gear tooth. How many times does the bicycle wheel turn when you make 20 turns of the pedal wheel?
  17. Cuboid
    kvader11 The sum of the lengths of the three edges of the cuboid that originate from one vertex is 210 cm. Edge length ratio is 7: 5: 3. Calculate the length of the edges.
  18. Average age
    candles_1 The company of five people has an average age of 46 years. The average age of the first four is 43 years. How many years has the fifth member of this company?
  19. Tetrahedron
    3sidespyramid What is the angle of the sides from the base of a three-sided pyramid where the sides are identical?
  20. Pendulum
    kyvadlo Calculate the length of the pendulum that is 2 cm lower in the lowest position than in the highest position. The length of the circular arc to be described when moving is 20cm.

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