Ratio + multiplication - examples

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. Chocolate
    cokolada Charlie bought 7 same chocolates for 14 Eur. How many euros he pay for 27 chocolates?
  2. Forestry workers
    forestry_workers In the forest is employed 63 laborers planting trees in nurseries. For 11 hour work day would end job in 43 days. After 14 days, 22 laborers go forth. How many days is needed to complete a planting trees in nurseries by others, if they will work 15 hours
  3. Bonus
    moeny Gross wage was 1762 USD including 22% bonus. How many USD were bonuses?
  4. Motion problem
    dragway From Košíc to Bratislavy go car at speed 76 km/h. From Bratislavy to Košíc go another car at speed 60 km/h. How many minutes before the meeting will be cars 22 km away?
  5. Cyclist
    cyclist_2 A cyclist passes 88 km in 4 hours. How many kilometers he pass in 8 hours?
  6. Store
    pave One meter of the textile were discounted by 2.4 USD. Now 6 m of textile cost as before 3 m. Calculate the old and new price of 1 m of the textile.
  7. Motion
    cyclist_1 If you go at speed 6.1 km/h, you come to the station 51 minutes after leaving train. If you go by bike to the station at speed 17 km/h, you come to the station 43 minutes before its departure. How far is the train station?
  8. Server
    p_pro Calculate how many average minutes a year is the web server is unavailable, the availability is 99.99%.
  9. Blood
    krv In human body the blood is about 7.7% body weight. How many kilograms of blood is in the human body with weight 96 kg?
  10. Chickens
    chickens 4 chickens give 4 eggs in 4 days. How many eggs can give 8 chickens for 8 days?
  11. Observer
    ohrada The observer sees straight fence 100 m long in 30° view angle. From one end of the fence is 119 m. How far is it from the another end of the fence?
  12. ŽSR
    luzianky Calculate fixed annual personnel costs of operating monorail line 106 km long if every 5 km is station, which serve three people - one dispatcher and two switchman in 3-shift operation. Consider the average salary of the employee 847 €.
  13. Youth track
    tunel Youth track from Hronská Dúbrava to Banská Štiavnica which announced cancellation attracted considerable media attention and public opposition, has cost 6.3 euro per capita and revenue 13 cents per capita. Calculate size of subsidies to trip group of 17.
  14. School trip
    school_trip School trip cost 340.8 USD for one class (24 students). How much would cost a trip for two classes? (both classes together have 44 students)
  15. Numbers
    ten Determine the number of all positive integers less than 2937474 if each is divisible by 11, 23, 17. What is its sum?
  16. Cats
    cats Two cats caught two mice in two days. How many mouses will catch 6 cats for 6 days?
  17. Daily average
    weather_forecast Calculate the average temperature during the day, when 14 hours was 20 °C and 10 hours was 15 °C.
  18. Gear wheels
    gear Two gear wheels, which fit together have number of teeth z1=132 and z2=123. Calculate the speed of the first wheel, if the second wheel rotates 247 revolutions per minute.
  19. Profitable bank deposit 2012
    eurocoins Calculate the value of what money lose creditor with a deposit € 7700 for 4 years if the entire duration are interest 2.2% p.a. and tax on interest is 19% and annual inflation is 3.6% (Calculate what you will lose if you leave money lying idle at negative
  20. Discount
    sales_discount Product has been discounted twice by 14%. What is the total discount given?

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