Ratio - problems

On solving problems and tasks with proportionally we recommend hint rule of three. Rule of three (proportionality) help solve examples of direct and inverse proportionality. Three members makes possible to calculate the fourth - unknown member.
  1. Circles
    two_circles The areas of the two circles are in the ratio 1:15. The larger circle has diameter 25. Calculate the radius of the smaller circle.
  2. Sea water
    sea_1 Seawater contains about 7% salt. How many dm3 of distilled water we must pour into 14 dm3 of sea water to get water with 1.7% salt?
  3. One sixth
    one_sixth How many sixth are two thirds?
  4. Discounts on rail (ZSSK)
    preukazy_zssk The railway company ZSSK offers a discount of 40% (JUNIOR RAILPLUS EURO
  5. Election mathematics
    statny-znak-sr_1 In elections, 6 political parties received this shares of voters: strana A 69.4 %strana B 11.2 %strana C 10.2 %strana D 7.6 %strana E 1.6 % Calculate what the shares acquired in the parliament, if a quorum is 5%.
  6. Plan of the village
    mapa_1 Plan of the municipality in 1:1000 scale has plotted garden with dimensions 25 mm and 28 mm. Determine the area of gardens in ares in reality.
  7. Minute angle
    watch Determine size of angle, which takes minute hand for 90 minutes.
  8. Ultra expensive ramps
    rampy_1 The village Čakajovce have two level railway crossings (the ramps), the railway company ZSR decided to replace it. The price for upgrading the two crossings is 302065 Euros. Calculate how many houses for 94000 euros is possible to obtain at this price. Ca
  9. Glass
    sklo At the glass shop we have to cut 8 sheets of glass. Each was shaped a square with sides of 18 cm. We paid 44 CZK. How much is a 1 m2 of glass?
  10. Family and age ratios
    family_1 Age of father and son are in the ratio 10:3; age of father and daughter are in the ratio 5:2. How old is father and son, if daughter is 20 years old? In what ratio is age sister and brother?
  11. Divers
    diving 24-member group of divers carries the air for 11 hours of diving. 4 members of the expedition sick or wasn't came. How many hours is sufficient air to other divers?
  12. Suit
    oblek The suit cost 218 euros. How much cost the pants if it is 40% cheaper than the jacket.
  13. Wheels
    tractor Small tractor wheel with a diameter of 60 cm must be rotated 8 times to overcome some pathway. How many times must turn the big tractor wheel with a radius 60 cm to overcome the same distance?
  14. Median
    tazisko The median of the triangle QRS is away from vertex S 63 cm. Calculate the length of the median, which start at S.
  15. Smallest internal angle
    angles_3 Calculate what size has the smallest internal angle of the triangle if values of angles α:β:γ = 3:4:8
  16. Train
    vlak_meskajuci The train passes part of the line for 116 minutes at speed 55 km/h. What speed would have to go in order to shorten the driving time of 11 minutes?
  17. Painters
    maliri 15 painters painted fence for 280 minutes. For how many minutes paint half of this fence 12 painters?
  18. Euros
    fractal_1 Michal, Peter, John and Lenka got together 2,400 euros. They share an amount in ratio 2:6:4:3. How many got each of them?
  19. Tree shadow
    tree2_1 Tree perpendicular to the horizontal surface has a shadow 8.32 meters long. At the same time meter rod perpendicular to the horizontal surface has shadow 64 cm long. How tall is tree?
  20. Beer
    piva After three 10° beers consumed in a short time there are 7.4 g of alcohol in 5 kg adult human blood. How much is it per mille?

Do you have interesting mathematical problem 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.