Examples for 8th grade - page 18

  1. Coin and die
    die Flip a coin and then roll a six-sided die. How many possible combinations are there?
  2. Pumps
    water_pump Pump that draws water at velocity 3.5 liters per second water from a construction trench take 35 minutes. a) Find out how many minutes the water would run out of the trench pump that draws 7.4 liters of water per second. b) What is the pumping velocity wo
  3. Hollow sphere
    sphere_2 Steel hollow sphere floats on the water plunged into half its volume. Determine the outer radius of the sphere and wall thickness, if you know that the weight of the sphere is 0.5 kg and density of steel is 7850 kg/m3
  4. Christmas Day
    stedryd In leap years was 53 Sundays. On what day of the week fell to Christmas Day?
  5. Slope of the pool
    swimming_pool Calculate slope (rise:run) of the bottom of swimming pool long 40 m. Water depth at beginning of pool is 1.15 m (for children) and depth at end is 1.92 m (for swimmers). Slope express as percentage and as angle in degrees.
  6. 3y inflation
    bread Price of the medicament rise in the first year by 8%, the second year fell by 4% and in the third year increased by 10%. Calculate the average annual increase in price of the medicament.
  7. Road
    route-66 Average climb of the road is given by ratio 1:29. By what angle road average climb?
  8. Mystery of stereometrie
    Tetrahedron Two regular tetrahedrons have surfaces 56 cm2 and 126 cm2. In what ratio is their volumes? Write as a fraction and as a decimal rounded to 4 decimal places.
  9. Divisibility
    dots Determine the smallest integer which divided 8 gives remainder 6 when divided 19 gives remainder 9 and when divided by 11 gives remainder 2.
  10. Hexagonal pyramid
    Hexagonal_pyramid Calculate the volume and the surface of a regular hexagonal pyramid with a base edge length 3 cm and a height 5 cm.
  11. Drunk man
    drunk-man Drunkman has 2.1‰ of alcohol in the blood. How many grams of alcohol has in blood, if he have 6 kg of blood?
  12. Lid
    drywell What is the weight of concrete cover (lid) to round shape well with a diameter 1.3 m, if the thickness of the cover is 15 cm? 1 m3 of concrete weighs 2190 kg.
  13. Sea
    ship How far can you see from the ship's mast, whose peak is at 11 meters above sea level? (Earth's radius is 6370 km).
  14. Electronics: Resistors in parallel
    resistors_1 From relation for calculating the resistance of parallel combination of resistors: ? Calculate the R, if R1 = 8kΩ a R2 = 18kΩ
  15. Purchase
    cart Mother bought 5 boxes of milk and 7 kg of potatoes and paid a total CZK 147. Aunt bought 7 boxes of milk and 3 kg of potatoes and paid 131 CZK. What is the price of one carton of milk and 1 kg of potatoes? How CZK together would have saved if bought at the
  16. Lines
    bus Five bus lines runs at intervals 3, 5, 10, 11, 13 minutes. In the morning, suddenly start at 7:00. After how many minutes the bus lines meet again?
  17. Nine-gon
    9gon_1 Calculate the perimeter of a regular nonagon (9-gon) inscribed in a circle with a radius 20 cm.
  18. Elevation
    horizon_diagram What must be the elevation of an observer in order that he may be able to see an object on the earth 814 km away? Assume the earth to be a smooth sphere with radius 6378.1 km.
  19. Pit
    ihlan_zrezany Pit has shape of a truncated pyramid with rectangular bases and is 2.8 m deep. The length and width of the pit is the top 3 × 1.5 m bottom 1 m × 0.5 m. To paint one square meter of pit we use 0.3 l of green colour. How many liters of paint is needed when w
  20. AVG of INT
    seq_moon What is the average of the integers from 7 throuht 15 inclusive?

Do you have interesting mathematical example that you can't solve it? Enter it and we can try to solve it.



To this e-mail address we will reply solution; solved examples are also published here. Please enter e-mail correctly and check whether you don't have a full mailbox.