Examples for 8th grade

  1. Filament of bulb
    bulb _1 The filament of bulb has a 1 ohm resistivity and is connected to a voltage 220 V. How much electric charge will pass through the fiber when the electric current passes for 10 seconds?
  2. 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.
  3. Volume and body diagonal
    kvader11_11 Calculate how much the volume and body diagonal of the cuboid decrease if we reduce each of its three edges a, b, c by 18%?
  4. Garden fence
    zahrada The garden has the shape of a rectangular triangle with an area of 96 square meters and a 16 m long one leg. How many meters of the fence need to be fenced?
  5. Two unknown numbers
    numbers_49 One number is 2 less than a second number. Twice the second number is 14 less than 5 times the first. Find the two numbers.
  6. Endless lego set
    lego_2 The endless lego set contains only 6, 9, 20 kilograms blocks that can no longer be polished or broken. The workers took them to the gym and immediately started building different buildings. And of course, they wrote down how much the building weighed. The
  7. Highway tunnel
    tunnel_1 The highway tunnel was built from two ends in the north-south direction. The average daily performance of the "northern party" rasters was higher than the average daily power of the "southern party" of the rasters. After 55 business days, both parties met
  8. 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.
  9. Two workers
    workers_20 Two workers should fulfill certain task together for 5 days. If the first worker increased their performance twice and second twice fell, it took them just four days. For how many days would handle the entire task first worker himself?
  10. 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.
  11. T-shirts and hat
    usd_9 5 t-shirts and a hat cost £62.00 2 t-shirts and a hat cost £29.00 How much does a t-shirt cost ? How much does a hat cost ?
  12. Unknown number
    eq222_5 If I reduced the sum of the numbers 70 and the unknown number three times, I would get 100. what is the unknown number?
  13. Train delay
    train_freight_4 The train should be in the station for 10 minutes. It still has 32 km left. What is the expected delay if the train travels in 2 minutes 3 km except for the last section where it is 2 km in 5 minutes.
  14. Conical area
    cones_2 A right angled triangle has sides a=12 and b=19 in right angle. The hypotenuse is c. If the triangle rotates on the c side as axis, find the volume and surface area of conical area created by this rotation.
  15. Fence and scale
    ctverec_mo_4 The garden with 80 m of fencing is draw on plan as a square with a side length of 4 cm. At what scale is this plan made?
  16. Quadrangular pyramid
    komoly Calculate the surface area and volume of a regular quadrangular pyramid: sides of bases (bottom, top): a1 = 18 cm, a2 = 6cm angle α = 60 ° (Angle α is the angle between the side wall and the plane of the base.) S =? , V =?
  17. Substitution
    eq1_5 solve equations by substitution: x+y= 11 y=5x-25
  18. Unknown numbers
    eq222_3 The sum of two consecutive natural numbers and their triple is 92. Find these numbers.
  19. Tangent
    tetiva33 What distance is the tangent t of the circle (S, 4 cm) and the chord of this circle, which is 6 cm long and parallel to the tangent t?
  20. Simple equations
    enc2 Solve system of equations: 5x+3y=5 5x+7y=25

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