Ratio - 7th grade (12y) - math 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 make possible to calculate the fourth - unknown member.

Number of problems found: 272

  • Coke and coal
    coal 20.1 tons of coke is produced from 30 tons of black coal. How much coke is made from 1 kilogram of coal?
  • Everyone drinks the same
    beers 24 bricklayers drink 72 beverage bottles a day at the construction site. How many bottles would 19 bricklayers need? Everyone drinks the same.
  • Chimney and tree
    shadow Calculate the height of the factory chimney, which casts a shadow 6.5 m long in the afternoon. At the same time, a 6 m high tree standing near it casts a shadow 25 dm long.
  • The plan
    city The plan of the housing estate is in three scales 1: 5000,1: 10000,1: 15000. The distance between two points on a plan with a scale of 1: 10000 is 12 cm. What is this distance on the other two plans? What is this distance?
  • Twice of radius
    gule How many times does the surface of a sphere decrease if we reduce its radius twice?
  • Pizza
    pizza Three siblings ordered one pizza. Miška ate a quarter of the whole pizza. Lenka ate a third of the rest and Patrik ate half of what Lenka had left. They had the rest packed up. How much of the pizza did they pack? Write the result as a fraction.
  • Rate 3
    time_1 A liquid is heated at a rate of 5 degrees Celsius per minute. If the temperature now is at 39 degrees Celsius, after how long will the temperature be 94 degrees Celsius?
  • Lookout tower
    marhat Calculate the height of a lookout tower forming a shadow of 36 m if at the same time a column 2.5 m high has a shadow of 1.5 m.
  • Mixing 5
    milk Carlos mixed 4/15 of chocolate syrup with 1/2 of milk. Determine the reasonable estimate of the total amount of liquid
  • Profitable company
    penize Three businessman decide to open up their own company. They agree to distribute the yearly profits made in the same ratio as their initial investments. They invest R 50 000, R 75 000 and R25 000, respectively. The profit made by the company in the first y
  • A cliff
    cliff A line from the top of a cliff to the ground passes just over the top of a pole 5 ft high and meets the ground at a point 8 ft from the base of the pole. If the point is 93 ft from the base of the​ cliff, how high is the​ cliff?
  • Divide in ratio
    lines_2 Line segment AB 12 cm long divide in a ratio of 5: 3. How long are the individual parts?
  • Diggers
    workers_1 The excavation was carried out in 4 days and 5 workers worked on it for 7 hours a day. Determine how long it would take to excavate if 7 workers worked on it 8 hours a day.
  • Volume of sphere
    sphere_in_cube How many times does the volume of a sphere increase if its radius increases 2 ×?
  • The dough
    cesto The dough contains water, flour, and sugar. Water and flour in a ratio of 2: 3, flour, and sugar in a ratio of 2: 1. Determine the ratio of all three components of the dough.
  • Ducats
    dukat The king divided the ducats to his three sons in a ratio of 2: 5: 4. How many ducats the king divided them if the youngest received 260 ducats, which was the least of all sons.
  • The angles ratio
    123_triangle The angles in the ABC triangle are in the ratio 1: 2: 3. find the sizes of the angles and determine what kind of a triangle it is.
  • Ages
    calendar Father is 36 years old, his daughter is 4 years old. Write down the ratio of the age of father and daughter. In what ratio will the ages of father and daughter after 4 years?
  • Age of family
    age The age of father and son is in the ratio 10: 3. The age of the father and daughter is in ratio 5: 2. How old are a father and a son if the daughter is 20?
  • Gears
    bicycle_gears_2 The front gear on the bike has 32 teeth and the rear, on the wheel, has 12 teeth. How many times does the rear wheel of the bike turns if you turn the right pedal 30 times? What distance will you go if the circumference of the bicycle wheel is 250 cm?

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