Examples for 8th grade - page 17

  1. Washing machine
    washing_masine The price of washing machine was decreased by 24% and then by 59 € due small sales. After two price decreases cost € 300. How much was originally cost?
  2. Bits, bytes
    bits Calculate how many different numbers can be encoded in 16-bit binary word?
  3. Beer permille
    pivo In the 5 kg of blood of adult human after three 10° beers consumed shortly after another is 6.6 g of the alcohol. How much is it as per mille?
  4. Jan
    Honza Jan is 13 years and Peter 21 years old. For how many years will their ages in the ratio of 7:9?
  5. Scouts
    skauti_1 The boys from scout group traveled 3 days distance 105 km. Every day walked 1.3 km less than the previous day. How many kilometers scouts walked in the first day?
  6. Similarity
    rectangles_1 Rectangle ABCD has dimensions of 9 cm and 6 cm. Rectangle PQRS has dimensions 7 cm and 8 cm. Determine coefficient of the similarity k of the rectangles, if they aren't similar enter zero as the coefficient of similarity.
  7. Newton's task
    cow Grass grows in the meadow equally fast and evenly. It is known that 58 cows graze meadow for 30 days and 80 cows by 19 days. How many cows graze meadow for 6 days?
  8. Hole
    cube_w_hole In the center of the cube with edge 15 cm we will drill cylinder shape hole. Volume of the hole must be 28% of the cube. What drill diameter should be chosen?
  9. Volleyball
    volejbal 8 girls wants to play volleyball against boys. On the field at one time can be six players per team. How many initial teams of this girls may trainer to choose?
  10. Wood
    rubanie_dreva Peter chops wood. If they cut down a half hours a day he ended work in 9 days. But Peter needs to end work 3 days earlier. How many minutes a day should cut down?
  11. Strawberries
    strawberries Father collects strawberries himself in 4 hours, son in 10 hours. How long will it take them along when dad comes to help son collect strawberries after 4 hours?
  12. Workman - shift
    favorit_skoda The worker produces 300 components per shift. How many components would be produced in 18 shift, if his performance gradually increased every shift by 3 components?
  13. Inflow - outflow
    water_barrels The tank will fill by inflow for 93 minutes and empties by outflow for 104 minutes. How long take to fill tank if it is also opened the inflow and outflow?
  14. Car range
    Lupo_3L_TDI.JPG Calculate the maximum range of car, if you can spend 25 euros, price of diesel is 1.55 Eur/l and car consumption is 6.4 l/100 km.
  15. Tangents
    tangents To circle with a radius of 98 dm from the point A guided two tangents. The distance of both points of contact is 155 dm. Calculate the distance from point A and circle centre.
  16. Painting rooms
    palma_1 If Dano paint three hours daily given work he complete in 7.5 days. How many hours a day would have to work to finish the job 1.5 days earlier?
  17. Trip
    pomarancovy-dzus On the trip drank 3/10 of pupils tea, 2/5 cola, 1/4 mineral water and remaining 3 juice. How many students were on the trip?
  18. Water tank 2
    tank_1 Water tank cuboid is 12 meters long and 6.5 meters wide and 1.2 meters high. How many hectoliters are in the tank when it is filled to 71%?
  19. Basements
    Spider-and-Fly In the first basement is more flies than the spiders, the second vice versa. Each basement had spiders and flies together 100 feet. Determine how many could be flies and spiders in the first and second basement. PS. We only need, when you write how many.
  20. Mushrooms
    mushrooms-01 For five days, we have collected 410 mushrooms. Interestingly every day we have collected 10 mushrooms more than the preceding day. How many mushrooms we have collected during 4th 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.