9th grade (14y) + expression of a variable from formula - examples

  1. Trapezoid 15
    trapezoid3 Area of trapezoid is 266. What value is x if bases b1 is 2x-3, b2 is 2x+1 and height h is x+4
  2. Isosceles right triangle
    IsoscelesRightTriangle Contents of an isosceles right triangle is 18 dm2. Calculate the length of its base.
  3. Isosceles triangle
    triangles_8 Calculate area and perimeter of an isosceles triangle ABC with base AB if a = 6 cm, c = 7 cm.
  4. Cylinder - h
    cylinder_2 Cylinder volume is 129 cm3. Base radius is 3 cm. Calculate the height of the cylinder.
  5. MO SK/CZ Z9–I–3
    ball_floating_water John had the ball that rolled into the pool and it swam in the water. Its highest point was 2 cm above the surface. Diameter of circle that marked the water level on the surface of the ball was 8 cm. Determine the diameter of John ball.
  6. Painters
    natieraci Five painters painting the fence for eight days. How many days over will take work if paint the fence only four decorators?
  7. Harvesters
    kombajny The first harvester reaps the grain from land for 24 hours, the second harvester for 16 hours. For how many hours will take harvest by two harvesters, but the second harvester started working four hours later than the first?
  8. Cleaners
    clean Milan would clean up the room for 2.5 hours, Eric would take 10 hours. How long they swept the room together?
  9. Perimeter and legs
    RT_triangle Determine the perimeter of a right triangle if the length of one leg is 75% length of the second leg and its content area is 24 cm2.
  10. Chocholate pyramid
    pyramid_choko How many chocolates are in the third shelf when at the 8th shelf are 41 chocolates in any other shelf is 7 chocolates more the previous shelf.
  11. Prism X
    hranol The prism with the edges of the lengths x cm, 2x cm and 3x cm has volume 48000 cm3. What is the area of surface of the prism?
  12. Rhombus diagonal
    rhombus2_1 Area of rhombus is 417. One diagonal measures 45, find length of other diagonal.
  13. Fire tank
    fireman Whole fire tank was discharged once in 2 days by first out by second in $n days. Once firefighters pumped out 1/9 of water out from the tank and then let the water flow out both drain. How long take empty the tank?
  14. IS trapezoid
    trapezoid_ABCD Calculate the length of diagonal u and height v of isosceles trapezoid ABCD, whose bases have lengths a = |AB| = 26 cm, c = |CD| = 5 cm and legs b = d = |BC| = |AD| = 19 cm.
  15. 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.
  16. Cows
    cow_3 Agricultural cooperative has increased the number of housed cows by 14% to 285 units. By how many cows increased agricultural cooperative the number of cows?
  17. Vinegar
    vinegar_1 What percentage vinegar we get if we mix 1 if dm³ eight percent vinegar with 1.5 dm³ six percent vinegar?
  18. Chord
    chord In a circle with radius r=11 cm is chord 4× longer than its distance from the center. What is the length of the chord?
  19. Four swords
    fight Obelix has three helmets, four swords and five shields. How many swords must make at the blacksmith forge Metallurgix to be able to walk another 90 days in unique armor?
  20. Pot
    valec_hrnec Calculate the height of 3 liter pot with shape cylinder with a diameter of 10 cm.

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.