Examples for 8th grade - page 30

  1. Water level
    grp-gridimage-77cb37 The glass container has a cuboid shape with dimensions of the bottom 24 cm and 12 cm. The height of water is 36 cm. Calculate the volume of the body, which are sunk into the water if the water level rise by 3 cm.
  2. Numbers
    primes Write smallest three-digit number, which in division 5 and 7 gives the rest 2.
  3. Mukls
    Chinese women workers The working group, in which 6 workers would ordered job completed within 21 working days. How many workers must be accept yet that the contract will be completed in 14 working days?
  4. Parking
    bus_and_car 120 vehicles parking on the morning. Pasenger car is charged 20 CZK, 50 CZK per bus. The guard collected for parking 2640 CZK in total. How many cars and how many buses stood in the parking?
  5. Around the flowerbed
    roses Around a rectangular flowerbed with dimensions 5.25 m and 12.5 m are to be planted roses equally spaced so that the roses found in every corner of the flowerbed and consumed them as little as possible. a) At what distance are planted roses? b) How many ro
  6. Plan scale
    geodet At what scale is drawn plan of the building, where one side of the building is 45 meters long is on the plan expressed by a straight line 12 mm long.
  7. Chalet
    turancar_autobus The children were on a school trip to the mountain . One third of the journey went by the train and continue by bus. When you get off the bus, they remained a third of the distance they traveled by bus. What part of journey children went by the bus (wrote
  8. The professor's birthday
    prof_einstein Professor of mathematics had 36 birthdays. The director congratulated him. The professor asked the director: "And how old are you?" The director replied: "I'm exactly twice as many years than you were when I was old as to you today." How old is the direc
  9. Scale
    valec_vykres Cylinder was drawn in scale 7:1. How many times is the volume of the cylinder smaller in reality?
  10. Efficiency
    engine_lap A certain device consumes 93 kW and delivers 77 kW. Find its efficiency.
  11. ŽSR
    luzianky Calculate fixed annual personnel costs of operating monorail line 106 km long if every 5 km is station, which serve three people - one dispatcher and two switchman in 3-shift operation. Consider the average salary of the employee 847 €.
  12. Estate
    mapa Estate shaped rectangular trapezoid has bases long 19 m , 66 m and perpendicular arm 46 m. Calculate how long is its fence.
  13. Solution
    chemia What amount of 80% solution and what amount of water is needed to mix in order to obtain two liters of 60% solution of this mixture?
  14. Assistant
    psaci-stroj Assistant rewrote 15% of the entire manuscript in 12 hours. How many hours must still write to rewrite the rest of the manuscript?
  15. Disinfecting solution
    desinfect How much distilled water is necessary to pour into 500 ml of 33% hydrogen peroxide solution to obtain 3% disinfecting solution?
  16. Apprentice
    ucen Worker and apprentice execute the work for 6 hours. Worker performs himself in 10 hours. How long do the work of an apprentice?
  17. Spirit
    lieh From 55% and 80% spirit we would like to produce 0.2 kg of 60% spirit. How many of them we must use in a solution?
  18. Bathroom
    koupelna How many CZK we pay for lining the perimeter walls of the bathroom with rectangular shape with dimensions 3.5 m and 4 m, high 1.5 m if 1 square m tile cost 300 CZK?
  19. Vacation
    motion Parents piggybacking children on vacation to its grandmother and grandfather at a city distant 150 kilometers. They agreed to meet halfway. Parents will be travel at 90 km/h, grandmother and grandfather at 60 km/h. Parents depart at 12:00 hours. When grand
  20. Pot
    valec_hrnec Calculate the height of 3 liter pot with shape cylinder with a diameter of 10 cm.

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