Examples for 8th grade - page 29

  1. Inscribed triangle
    obluk To a circle is inscribed triangle so that the it's vertexes divide circle into 3 arcs. The length of the arcs are in the ratio 2:3:7. Determine the interior angles of a triangle.
  2. Pennies
    Toliar.preview 800 pennies have the same value as 100 ducats. 100 pennies have the same value as 250 tolars. How many ducats has the same value as 100 tolars?
  3. Snowman 2
    snowman_1 On the medal, which has the shape of a circle with a diameter 17 cm is sketched snowman so that the following requirements are met: 1. snowman is composed of three circles, 2. space over snowman is the same as under it, 3. diameters of all circles express
  4. Diamond
    rhombus2_2 Determine the side of diamond if its content is S = 500 cm2 and one diagonal u2 = 46 cm.
  5. 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?
  6. Disinfecting solution
    desinfect How much distilled water is necessary to pour into 500 ml of 33% hydrogen peroxide solution to obtain 3% disinfecting solution?
  7. Coffee
    arabica_robusta Coffee merchant has coffee robusta and arabica species. 1 kg Robusta worth 450 CZK, Arabica 1 kg is 300 CZK more expensive. Calculate how many kilograms of Robusta and Arabica will need to produce 30 kg of the mixture so that the mixture cost is 490 CZK p
  8. Probability - tickets
    zreby What is the probability that when you have 25 tickets in 5000 that you wins the first (one) prize?
  9. 3sides prism
    prism_3 The base of vertical prism is an isosceles triangle whose base is 10 cm and the arm is 13 cm long. Prism height is three times the height of base triangle. Calculate the surface area of the prism.
  10. Tank No 8
    tank1 Tank is filled by one inlet valve with a flow rate of 12 liters per second in 72 minutes. How long take the tank to fill, if we open half an hour after one more inlet?
  11. Ski tow
    ski_tow The ski club has 168 pupils and used lift with 60 seats, while students always follow the same sequence in filling seats. How many times while riding a ski lift skier sitting in the same seat as the first run?
  12. Deposit 3
    interest_money After a year had Martin on bank account € 1764. What was the interest rate when the initial deposit was € 1581?
  13. Soup
    polevka 61% of pupils at the school to eat in the canteen, 1/61 of students who eat in the canteen eat lunch soup. a) What percentage of pupils who eat in the canteen and eat soup for lunch? b) What percentage of all pupils of school eat lunch soup?
  14. Roots
    square_roor Calculate the square root of these numbers:
  15. Alcohol 2
    alko Two types of alcohol one 70% and second 61% give 11 liters of 57% alcohol. How many liters of each type are in the mixture?
  16. Divers
    diving 24-member group of divers carries the air for 11 hours of diving. 4 members of the expedition sick or wasn't came. How many hours is sufficient air to other divers?
  17. Rising price
    book The book first become more expensive by 5 euros. New price was later increased by 13%. After the second price increase book cost 47 euros. What was the original price of the book?
  18. Pool
    bazen Mr. Peter build a pool shape of a four-sided prism with rhombus base in the garden. Base edge length is 6 m, distance of the opposite walls of the pool is 5 m. Estimated depth is 193 cm. How many hectoliters of water consume Mr. Peter to fill the pool?
  19. Slope
    slope What is the slope of the line defined by the equation -4x -2y = -7 ?
  20. 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?

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