Examples for 8th grade - page 19

  1. MO - triangles
    metal On the AB and AC sides of the triangle ABC lies successive points E and F, on segment EF lie point D. The EF and BC lines are parallel and is true this ratio FD:DE = AE:EB = 2:1. The area of ABC triangle is 27 hectares and line segments EF, AD, and DB se
  2. 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
  3. Root
    sq_root Use law of square roots roots: ?
  4. Lock
    combination-lock Combination lock will open when the right choice of 5 numbers (from 1 to 12 inclusive) is selected. A. How many different lock combinations are possible? B. Is he combination lock named appropriately?
  5. Nine-gon
    9gon_1 Calculate the perimeter of a regular nonagon (9-gon) inscribed in a circle with a radius 20 cm.
  6. Two balls
    balls-inside-cylinder Two balls, one 8cm in radius and the other 6cm in radius, are placed in a cylindrical plastic container 10cm in radius. Find the volume of water necessary to cover them.
  7. Event probability
    dices_1 The probability of event G in 9 independent experiments is 0.48. What is the probability that the event G occurs in one experiment (probability is same)?
  8. Intersections
    intersect_circles How many intersections have circles with radius 12 dm and 17 dm, if the distance of their centers is 20 dm.
  9. Shots
    broky 2000 lead shots with diameter 2 mm is decanted into a ball. What is it diameter?
  10. Dices
    dices_2 We will throw two dice. What is the probability that the ratio between numbers on first and second dice will be 1:2?
  11. Box
    uhlopriecka Calculate the angle between box base 5 x 7 and body diagonal length 14.
  12. Balance
    balance_weight The rod are 1.7 m long hanging weights 2 kg and 12 kg on ends. Where are centre of rod (distance from weight 2 kg) to be in balance?
  13. Election mathematics
    statny-znak-sr_1 In elections, 6 political parties received this shares of voters: strana A 69.4 %strana B 11.2 %strana C 10.2 %strana D 7.6 %strana E 1.6 % Calculate what the shares acquired in the parliament, if a quorum is 5%.
  14. The bridge
    circle_dam Across the circle lakepasses through its center bridge over the lake. At three different locations on the lake shore are three fishermen A, B, C. Which of fishermen see the bridge under the largest angle?
  15. Do you solve this?
    rectangles_4 Determine area S of rectangle and length of its sides if its perimeter is 96 cm.
  16. Circumscribing
    thales Determine the radius of the circumscribed circle to the right triangle with legs 3 cm and 3 cm.
  17. Reservoir + water
    cuboid_water Reservoir completely filled with water weighs 13 kg. After pouring off three quarters of the amount of water weights 4 kg. Calculate the weight and volume of the reservoir.
  18. Isosceles III
    demos The base of the isosceles triangle is 24 cm area 416 cm2. Calculate the perimeter of this triangle.
  19. Felix
    astronaut Calculate how much land saw Felix Baumgartner after jump from 22 km above ground. The radius of the Earth is R = 6378 km.
  20. Christmas Day
    stedryd In leap years was 53 Sundays. On what day of the week fell to Christmas Day?

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.