Maths practice for 12-year-olds - page 55 of 355

Number of problems found: 7085

Spider fly legs
There are spiders and flies on the window. They have a total of 38 legs. How many spiders and flies are there if a spider has 8 legs and a fly has 6? Just give one solution.
Class weight average
There were 31 students in the class, and the arithmetic average weight was 43 kg. Calculate the average weight in the class if a student weighing 91 kg has been added to the class.
Plot plan price
On the 1:75 scale plan, the building plot is a rectangle with 60 cm and 50 cm dimensions. If 1 m² of land costs 80 euros, what is the price of the land?
Pepa book pages
The book has 500 pages. Pepa has read half as many pages as he has left. How many pages did Pep read?
Barrel bucket kettle
The internal volume of the barrel is 15 times greater than the bucket's volume. The volume of the bucket is 5 times the volume of the kettle. We took a third of the water from a barrel, leaving 60 liters in it. Calculate the volume of the kettle in liters
Amount eighth subtraction
What amount will I get if I subtract 1/8 from the amount of 30000?
Fabric width meters
Mrs. Smith bought 3.15 m of fabric 140 cm wide for a dress. How many meters of cloth will she need for the same 90 cm wide fabric dress? The result is rounded to whole meters.
Diesel tank filling
The diesel tank has a volume of 19.6 hl. The inflow oven, which flows 17.5 l per minute, was opened for 1.5 hours. How long does the inlet pipe need to be opened for the tank to be completely filled?
Truck car pursuit
At half past six in the evening, a truck left the warehouse at an average speed of 40 km/h. In 1.5 hours, a car drove behind him with an average speed of 70 km/h. How long and at what distance will the truck catch up from the warehouse?
Cylinder - curved area
The curved area of the rotary cylinder is three times greater than the area of one base of this cylinder. The radius of the base of the cylinder is 10 cm. What is the surface area of the cylinder?
Movie time remaining
The whole movie lasts 1 hour. The time left until the end of the film is half of the time that has already passed since the film's beginning. Calculate how many minutes are left until the end of the movie.
Milk butter kilograms
8 kg of butter is made from 20 hl of milk. How many kilograms of butter can be made from 450 l of milk?
Steel rope weight
Calculate the weight in kg of a steel rope 1.5 cm in diameter and 10 m long if one cubic centimeter of steel weighs 7.8 g
Car kinetic energy
Determine the kinetic energy of a car with a mass of 800 kg if it travels at a speed: a) 10 m/s b) 20 m/s
Body kinetic work
What work must be done to bring a body of mass of 2 kg lying on a smooth horizontal plane from rest to a speed of 2 m/s?
Vinegar acetic acid
Kitchen vinegar is an 8% solution of acetic acid in water. How many liters of acetic acid are needed to produce 275 liters of vinegar?
Jožko animal count
Jožko keeps dogs, guinea pigs, hamsters, and hares. A total of 24 animals. Of these, 1/3 are hamsters, 3/8 are guinea pigs, and 3/4 are not hares. How many dogs does Jožko have?
Teacher paper correction
The new teacher corrects papers for 9 hours, and the older one fixes them in 6 hours. How much will they repair together?
Class height average
There were 21 pupils in the class, and arithmetically, the average height of these pupils was 163 cm. Calculate what the average height in the class will be if: a) A 159 cm tall student was added to the class b) A 169 cm tall student left the class
Brass copper zinc
Brass is an alloy of copper and zinc in a ratio of 3:2. How much copper and zinc do you need to make 1 kilo of brass?

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