Examples for 8th grade - page 22

  1. OPT
    right_triangle_pythagoras What is the perimerer of a right triangle with the cathetuses 20 cm and 13 cm?
  2. Water inlets
    pipe Inlet valve with a flow rate of 12 liters per second is filled tank for 72 minutes. How long take to fill full tank if we open one more such valve half an hour after?
  3. Two workers
    Frog Two workers together execute some work in 10 days. The first worker would have done himself in 20 days. How many days would have done himself a second worker?
  4. Four pupils
    four_digit Four pupils divided $ 1938 so that the second received 20% less than the first, the third 1/6 less than a fourth and fourth $ 132 less than the first. How much money had each of them?
  5. Cable car 2
    lanovka_1 Cable car rises at an angle 39° and connects the upper and lower station with an altitude difference of 345 m. How long is the track of cable car?
  6. Perpendicular
    slopeplane What is the slope of the perpendicular bisector of line segment AB if A[-9,-8] and B[-8,0]?
  7. Cubes
    two_cubes Surfaces of cubes, one of which has an edge of 18 cm shorter than the other, differ by 7776 mm2. Determine the length of the edges of this cubes.
  8. Triangular prism
    hranol_3 Base of perpendicular triangular prism is a right triangle with leg length 5 cm. Content area of the largest side wall of its surface is 130 cm² and the height of the body is 10 cm. Calculate its volume.
  9. Diagonals
    diamond_math Rhombus has two diagonals e=11 dm and f=17 dm. Calculate the side angle and height of the rhombus.
  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. Monty Hall
    Monty_open_door Suppose you're on a game show, and you're given the choice of three doors: Behind one door is a car; behind the others, goats. You pick a door, say No. 1, and the host, who knows what's behind the doors, opens another door, say No. 3, which has a goat. W
  12. Area codes
    us_codes How many 6 digit area codes are possible if the first number can't be zero?
  13. Cuboid
    kvadr Find the cuboid that has the same surface area as the volume.
  14. Rhombus
    rhombus_4 Calculate the length of the diagonal AC of the rhombus ABCD, if its perimeter is 352 dm and the other diagonal BD has length 148 dm.
  15. Certificate
    ucitel There is 28 students in a class. From mathematics was'nt worse mark than 2. Average mark in mathematics was 1.4643. How many students have mark 1 and how many mark 2?
  16. Sphere - parts
    odsek_vusek Calculate the area of a spherical cap, which is part of an area with base radius ρ = 10 cm and a height v = 2.7 cm.
  17. Pharmacy
    lekarna At the pharmacy are in one container 20% solution in the second 50% solution of disinfectant. They need to prepare 24 L of 36-percent solution. What amount of solution from each container is needed to mix?
  18. Ladislav in Amsterdam
    jakob3 Ladislav was reward and went to conference in Amsterdam. Conferense fee was € 2184. Calculate how many books Ladislav could buy at the price of 42 and 28 euros if he don't want fill whole home library and he can buy only 63 books?
  19. Iron sphere
    sphere_1 Iron sphere has weight 100 kg and density ρ = 7600 kg/m3. Calculate the volume, surface and diameter of the sphere.
  20. Park
    park_voda In the newly built park will be permanently placed a rotating sprayer irrigation of lawns. Determine the largest radius of the circle which can irrigate by sprayer P so not to spray park visitors on line AB. Distance AB = 55 m, AP = 36 m and BP = 28 m.

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