Examples for 8th grade - page 80

  1. Lawns
    grass Before a sports hall are two equally large rectangular lawns, each measuring 40 m and 12 m. Maintenance of 10m² lawn cost 45 CZK yearly. On each lawn is circular flowerbed with a diameter 8 meters. How much money is needed each year to take on lawn care?.
  2. Tree shadow 3
    tree3_1 A 2-meter rod casts a shadow 3.2 m long. How high is a tree with a shadow of 14.4 m ?
  3. Earth and Sun
    sun_1 Earth is 150 million km away from the Sun, 300,000 km of sunlight travels in 1 second. How long will the light come from the Sun to the Earth?
  4. Three-digit
    seven How many three-digit natural numbers do not have the number 7?
  5. Bags
    kufor The first bag has a weight of 18 kg, the second bag is a one-third lighter than the first and the third bag has three times less the weight of all three bags together. Determine their weights.
  6. Hypotenuse
    sqrt Calculate the length of the hypotenuse of a right triangle with a cathetuses 71 cm and 49 cm long.
  7. Cuboid enlargement
    cubes_12 By how many percent increases the volume of cuboid if its every dimension increases by 30%?
  8. Cars 6
    car_15 At 9:00 am two cars started from the same town and traveled at a rate of 35 miles per hour and the other car traveled at a rate of 40 miles per hour. After how many hours will the cars be 30 miles apart?
  9. Divisible by 5
    175px-5th_MarDiv How many three-digit odd numbers divisible by 5, which are in place ten's number 3?
  10. Working together
    malovka_1 One painter paint the nursery in 10 days, the second in 8 days. How many days will the nursery be painted if they work together?
  11. Water reservoir
    vodojem The reservoir shape of a cylinder having a diameter 8 m and a height 2.8 m. The device indicates that the reservoir contains 800 hectoliters of water. Calculate how much % of volume is used.
  12. Scale 3
    cuboid_4 Miriam room is 3.2 meters wide. It is draw by line segment length 6.4 cm on floor plan. In what scale it is plan of the room?
  13. Equation
    serwisy_chemia_01 ?
  14. Angles in ratio
    angles_1 The size of the angles of the triangle are in ratio x: y = 7: 5 and the angle z is 42° lower than the angle y. Find size of the angles x, y, z.
  15. Body diagonal
    cubes3_1 Find the cube surface if its body diagonal has a size of 6 cm.
  16. Four friends
    money_10 Four friends shared the money. Vasek got 1/4 of the total amount. Tonda received 1/3 of the rest of the money, Joe got a half from the second residue and Jirka left 80. How much money get together?
  17. Factory
    factory_1 In the factory workers work in three shifts. In the first inning operates half of all employees in the second inning and a third in the third inning 200 employees. How many employees work at the factory?
  18. Remuneration
    cnb Total remuneration for workers is 47 000 CZK. The second worker received 20% more than the first and third 4000 CZK less than a second employee. How many CZK each received?
  19. Reciprocal equation
    img_reci_1 Determine the root of the equation: 9/x-7/x=1
  20. Masons
    Pat_a_Mat 1 mason casts 30.8 meters square in 8 hours. How long casts 4 masons 178 meters square?

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