Math practice for 13 year olds - page 82 of 428

Number of problems found: 8558

Painter house help
Four painters painted the house in 14 days. How long will it take if 2 more come to help after 5 days?
Rectangle dimension increase
The area of the rectangle is 81.25 cm². If we increase its length by 5 mm, its area increases by 4%. Determine its dimensions.
Square side reduction
A square has a side length of 25 cm. How big is its area if the side is reduced by 25%?
Quadrilateral triangle segment
The quadrilateral ABCD is symmetrical about the diagonal AC. The length of AC is 12 cm, the length of BC is 6 cm, and the interior angle at vertex B is right. points E and F are given on the sides AB, and AD so that the triangle ECF is equilateral. Determ
Circumference of edges
The hexagon pyramid has a circumference of 120 cm, and the length of the side edge is 25 cm. Calculate its volume.
Number percentage more
The number 420 is 20% more than the unknown number. What is the unknown number?
Number ratio sum
The ratio of the two numbers is 1:3. Half of the larger one is 135. What is the sum of the two numbers?
Part-time earnings soccer
I had 350 euros left over from the money I earned from the part-time job. I bought soccer cleats with half of the money I earned and a soccer ball with the other half. How much did I earn from the part-time job?
Purchase advantage comparison
Determine which purchase is more advantageous: ... ...
Banknote payment euros
Participants paid out 3,300 euros in 40 banknotes. Some were 50e, and others were 100e. How many were there?
Bus highway speed
Tourists traveled by bus to Croatia. They drove the highway in 8 hours at an average speed of 100 km/h. How fast would they cover it if they walked at an average speed of 120 km/h?
Map scale reduction
Cyril marked a square plot of land on a map with a scale of 1 ∶ 50,000 and calculated that its side corresponds to 1 km. He reduced the map on the copier so that the marked square had an area smaller by 1.44 cm² than on the original map. What was the scal
Younger Carlos
In 2005, Peter was three times as old as Carlos. In 2020, Carlos was half his age younger than Peter. In which year was Peter born and in which Carlos?
Painter fence work
Two painters are painting the factory fence together. If everyone worked alone, the first would finish the job in 16 days, the second in 20 days. When will they finish the work together?
Apricot peach purchase
We paid a total of 85 crowns for the purchase of 2.5 kg of apricots and 1.5 kg of peaches. A kilogram of peaches is CZK 2 cheaper than a kilogram of apricots. How much CZK was paid for the apricots?
Katka marble total
Katka has k marbles, Petra has 20 more marbles than Katka, and Lenka has 30 marbles less than Petra and Katka combined. How many marbles do they all have in total?
Free fall velocities
Calculate the instantaneous free fall velocities at the end of the 1st, 3rd, 5th, and 7th seconds. Compile the results in a table.
Spherical segment
Calculate the volume of the spherical segment and the surface area of the canopy if the radius of the sphere is r = 5 cm and the radius of the circular base of the segment ρ = 4 cm.
Circumscribed - sphere
A cube with a volume of 4096 cm³ is described and inscribed by a sphere. Calculate how many times the volume of the circumscribed sphere is greater than the inscribed sphere.
Pavla Irena age
Pavla is 2x older than Irena. Four years ago, Pavla was 6 times older than Irena was then. In how many years will the ages of Pavla and Irena be in the ratio of 4:3? Thanks

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