Ratio + time - 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: 98

Two xeroxes
The performances of the two copiers are in the ratio 3: 4. A machine with higher power will make 7,200 copies in one hour. How many copies will both machines make together in 5 hours?
Mr. Ben
Mr. Ben drives bricks to the construction site. If he drove three times a day, he would make bricks in 8 days. How many times a day would he go every day to be done 2 days earlier?
Everyone drinks the same
24 bricklayers drink 72 beverage bottles a day at the construction site. How many bottles would 19 bricklayers need? Everyone drinks the same.
On the
On the map of Europe made at a scale of 1: 4000000, the distance between Bratislava and Paris is 28 cm. At what time an airplane flying at 800 km/h will fly this journey?
Six workers
Six workers earned a total of CZK 12,600 per week on the construction site (5 working days). How much do 7 workers earn in 10 days with the same daily average salary?
Five combers
Five combers harvest 12 rows of strawberries in 4 hours. How many rows of strawberries will two combers harvest in 10 hours?
Age of family
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?
Diggers
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.
Worker's performance
15 workers paint 180 m fence in 3 days. In how many days will 9 workers paint a 360 m fence? We assume that each worker have the same, constant and unchangeable performance.
Father and daughter
Father is 36 years old, daughter is 20 years less. What will be the ratio between them when they are 10 years more?
Ages
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 ratio
Janko is 14 years old. The age ratio of Janka and Zuzka is 2: 3. What was the ratio seven years ago?
Rate 3
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?
Two trains
Two trains departed from City A and City B against each other. They met after some time. The first train then took 9 hours to reach city B, and the second train took 4 hours to reach city A. In what proportion were the train speeds?
Cheetah vs antelope
When the cheetah began chasing the antelope, the distance between them was 120 meters. Although the antelope was running at 72km/h, the cheetah caught up with it in 12 seconds. What speed was the cheetah running?
Kilowatt-hours
If the Lewis family used 648 kilowatt-hours of electricity in 12 days, how many kilowatts hours should they use in 24 days at the same rate of usage
Painters
Ten painters paint the school in 20 days. How many days do four painters paint the school at the same pace of work?
Tourist
A tourist walked an average speed of 3.5 km/h route in 6 hours. Calculate how many hours he would have passed at an average speed of 5.5 km/h.
Cook on gas
The gas cylinder will last for 30 weekends for 2 hours of daily cooking. How many days will we be able to cook on a new cylinder when we cook 3 hours a day?
The work
The work was to be done by 150 workers. At the beginning of their work, their number reduced by 40, which increased the time of work by 5 and 1/3 of the schedule. How long did work take?