Common work - 9th grade (14y) - math problems
- Five tractors
Five tractors plow the fields in 4.8 hours. How long will it take to plow the field when, after an hour and a half of work, two tractor drivers have been called up for another task?
- The coal
The coal stock would be enough to heat a larger room for 12 weeks, a smaller one for 18 weeks. It was heated for four weeks in both rooms, then only in a smaller one. How long was the coal stock enough?
The first worker would dig a trench in 6 hours. For the second, the same work would take 4 hours. How long did it take for the trench to be dug if they worked together?
The first bricklayer would build a wall in 3 days, the second in 4 days. The first bricklayer worked alone for a day, then the second bricklayer came to his aid and they finished the work together. How long did it take to build the wall?
- Working together
Two people will do the work in 12 days. They worked together for 8 days. Then only one worked for 10 days. How many days would each of them do the work if he worked alone?
- Hectares of forest
12 workers plant 24 ha of forest in 6 days. In how many days will 15 people and 12 people plant the same area?
- Aircraft angines
The two engines of the aircraft are enough to supply the fuel for five hours of operation. However, one of the engines has a malfunction and thus consumes one-third more fuel. How long can the plane be in the air before it runs out of fuel? After an hour
- Baking muffins
Aunt Polly is baking muffins at a speed of 4 muffins per minute. Tom comes into the kitchen when Aunt Polly has 12 muffins, and begins to eat these muffins at a speed of 6 muffins per minute. When he finally leaves the kitchen, there are 4 muffins at the
- Panel house
The construction company has two groups of workers. Group A has more members than B. Panel house was insulated by group A in 10 days. The same block of flats was insulated together in 6 days. How many days would group B block insulate?
- Two companies
The family ordered two companies to modify the garden. The first would be done in 20 days, the second would take 40% less time. How long will they work together if the second company started working when the first worked for 4 days?
5 children collect 4 liters of blueberries in 1.5 hours. a) How many minutes do 3 children take 2 liters of blueberries? b) How many liters of blueberries will be taken by 8 children in 3 hours?
- Two workers
One worker needs 40 hours to do a job, and the second would do it in 30 hours. They worked together for several hours, then the second was recalled, and the first completed the job itself in 5 hours. How many hours did they work together, and how much did
- Two water containers
In the first container, there are 200 m3 of water and in the second 40 m3. The first container will flow down at a rate of 10 m3 water per hour. At the same time flows to the second rate of 5 m3 per hour. After how many hours there will be three times les
- Three pumps together
One pump fills the tank in 1.5 hours, the second in 2 hours, and the third in 3 hours 20 minutes. How many minutes will the tank fill with three pumps if they work simultaneously?
- Working alone
Tom and Chandri are doing household chores. Chandri can do the work twice as fast as Tom. If they work together, they can finish the work in 5 hours. How long does it take Tom working alone to do the same work?
- Three tributaries
It is possible to fill the pool with three tributaries. The first would take 12 hours, the second 15 hours, and the third 20 hours. The day before the summer season began, the manager opened all three tributaries simultaneously. How long did it take to fi
- Six workers
Six workers planned to repair the roof in 5 days. After two days, two workers get sick. How long will the remaining workers complete the roof at the same rate of work?
- Four painters
The company sent four painters to paint the school. They should be done in 12 days. After three days, one painter got ill. How long will the remaining painters paint the school?
- Assembly parts
Nine machines produce 1,800 parts on nine machines. How many hours will it produce 2 100 parts on seven such machines?
- Seven workers
Seven workers clear the glade in 22 hours. How many workers would need to be done in 8 hours?