Math practice for 13 year olds - page 388 of 422
Number of problems found: 8438
- Painting school
Redecoration school had scheduled for four crew to 10 days. After two days, a single worker was ill. For how many days was the school painted when remain workers working with the same tempo? - Five tractors
Five tractors plow the field in 4.8 hours. How long would it take to plow this field if, after 1.5 hours of work, two tractors went to a different field? - Common cylinder
I've quite a common example of a rotary cylinder. Known: S1 = 1 m2, r = 0.1 m Calculate : v =? V =? Can you verify the results? - Wood
Wood contains 12% water. One m³ of wood weighs 650 kg. How many liters of water does it contain? - Uranium ore
Uranium ore contains 0.2% pure uranium, and pure uranium includes 0.07% fissile uranium. How many grams of fissile uranium has 7400 ton of uranium ore? - Cargo
The weight of the cargo car is 761 kg. The car's weight is 23% of the total weight of the car+cargo. What is the weight of the cargo load? - Influenza
For the first week of February, by influenza, 5% of children were in kindergarten. In the second week ill, nine next children, bringing the number of patients increased to 20%. How many children went to kindergarten? - Pumps
The first pump flows 16 liters per second into the basin by the second pump 75% of the first and by the third pump half more than the second. How long will it take to fill the basin with all three pumps simultaneously, a volume of 15 m³ (cubic meters)? - James
James paints a fence. If he painted every day, instead of 14 planks, he would do 16 one day earlier. How many planks have a fence altogether? - Unknown number 10
The number first increased by 30%, then by 1/5. What percentage we've increased the original number? - Potatoes 1537
Potatoes contain 65% starch. How many potatoes do we need to get 13 kg of starch? - Crowns
1180 crowns are divided into three: A got 20% less than B, and C got 15% more than B. How many got A, B, and C? - Repair company
The company repairs cars. On the first day, repair half of the contract; on the second day, half of the rest; and on the third day 8 residue cars. How many total cars did the company repair? - Family
Martin has just as brothers and sisters. But his sister Jana has two times more brothers than sisters. a) How many children are in this family? b) How many boys and how many girls are in the family? - Triangle midpoints
Determine coordinates of triangle ABC vertices if we know triangle sides midpoints SAB [0;3] SBC [1;6] SAC [4;5], its sides AB, BC, AC. - Square and circle
Into the square is an inscribed circle with a diameter of 10 cm. What is the difference between a circumference square and a circle? - Concentric circles
In the circle with diameter, 13 cm is constructed chord 1 cm long. Calculate the radius of a concentric circle that touches this chord. - Minute-hand
How long will a large (minute) hand travel on the clock for 48 minutes if its length is 56 cm? - Circle and hexagon
Calculate the radius of a circle whose circumference is 8.7 cm longer than the inscribed regular hexagon's circumference. - Again saw
We have a sculpture beam from the tree trunk with a rectangular cross-section with dimensions 91 mm and 87 mm. What is the trunk's smallest diameter?
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