Examples for 8th grade - page 84

  1. Class
    children_2 In a class are 32 pupils. Of these are 8 boys. What percentage of girls are in the class?
  2. Outer contact of circles
    nakres_2z Construct a circle k1 (S1; 1.5 cm), k2 (S2; 2 cm), and K3 (S3; 2.5 cm) so that they are always two outer contact. Calculate the perimeter of the triangle S1S2S3.
  3. Unknown number
    5nums_1 Determine the unknown number, which double of its fourth square is equal the fifth its square.
  4. Central park in city
    park The city park has the shape of a rectangle of 180 meters in length and 120 meters in width. People make their walk through the center of the park from one corner to the second. Calculate how many meters this way is shorter than they walked along the path.
  5. Alcohol mixture
    pipe2_2 Three liters of 96 percent alcohol we set up a certain amount of distilled water to form a 54-percent alcohol. How many liters of distilled water were used?
  6. Mushrooms
    huby_3 Fresh mushrooms contain 90% water, dried only 12%. How many kilograms of fresh mushrooms are needed for 5kg dried?
  7. PC disks
    diskette Peter has 45 disks in three colors. One-fifth of the disks are blue, red are twice more than the white. How much is blue, red and white disks?
  8. Rectangle
    obdlznik The length of the rectangle is 12 cm greater than 3 times its width. What dimensions and area this rectangle has if ts circumference is 104 cm.
  9. Scale of map
    map_9 James travels one kilometer in 12 minutes. The route walked for half an hour measured on the map 5 cm. Calculate how many kilometers James walked for half an hour. Find the scale of the map.
  10. Comparing salaries
    eura_5 Spouses compared salaries. Mrs. Janka found that a 20% higher salary than Mr Jaroslav. Together earned € 1,430. How much they earn each of them?
  11. Tailor master
    saty There are less than 50m of textile in the tailoring workshop. When cutting on a blouse (consumption 1.5m), no textile is left. When using a cloth (consumption of 3.2m), no textile is left. How many meters of textile are in a tailor's workshop?
  12. Rhombus
    kosostvorec_6 If we increase the rhombus side by 2.4 cm; its perimeter is 20 cm. How long was the side of the rhombus?
  13. Blueberries
    blackberries Miko and Anton have a total of 1,580 blueberries. Miko and Anton have them in the ratio 2: 3. Determine how much each of them has.
  14. Distilled water
    water2_1 Sea water contains 5% salt. How many distilled water should be pour to 40 kg of sea water so that the salt content is 2%. How many kilograms of 2% of sea water we get?
  15. Price saleoff
    2digits_1 Shoes standing y euros. At first they were discounted by 12% and then 50% of the new amount. After this double cheapening the cost was exactly 22 euros. Determine the original price of shoes.
  16. Square
    ctverec_mo_2 Calculate the perimeter and the area of square with a diagonal length 30 cm.
  17. Contract
    clocks_5 8 employees complete the contract for 65 hours. After 17 hours, 3 employees had to leave for another job. How many more hours will the job on contract be fulfilled?
  18. 3 masons
    cnb_1 3 masons received 7,700 CZK. The second half received 1/2 more than the first and third twice more than the second mason. How much they each got crowns?
  19. Two trains
    trains_1 There are two trains running the same distance. 1st train will travel it in 7 hours 21minutes. 2nd the train will travel 5 hours 57minutes and 34 seconds and it is 14 km/h faster than the first train. What are speeds of trains and how long is this railway
  20. Pyramid
    jehlan_4b_obdelnik The pyramid has a base rectangle with a = 6cm, b = 8cm. The side edges are the same and their length = 12.5 cm. Calculate the surface of the pyramid.

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