Math practice for 13 year olds - page 71 of 428

Number of problems found: 8558

Sapling species percentage
Volunteers planted saplings in the forest nursery; spruces made up 55% of all saplings; one-third were edible, and the rest were young pines. How many saplings did they plant if the number of saplings was greater than 1060 and less than 1090?
Reward ratio division
Three friends split the reward in the ratio of 3:5:7. One of them received exactly €49. How many euros did they get together?
Gear wheel rotation
Two gears mesh together. The larger wheel has 56 teeth, and the smaller wheel has 20 teeth. How many times does the smaller wheel turn if the larger wheel turns 15 times?
Log ratio division
A log 88 cm long is divided into 3 parts in the ratio 3: 2: 5. How big is each part?
Passenger train
At 9:15 AM, a passenger train passes the station at a speed of 75 km/h. At 10 o'clock, an express train passes through the same station in the same direction at a speed of 120 km/h. Both trains arrive at the same destination station at the same time. a) a
Cinema seat probability
Calculate the probability of the event that you sit in seats 1 to 30 in the cinema at: a) seat marked with a prime number b) seat marked with an even number c) a seat marked with a number divisible by 3 or 4
Staircase railing length
How long is the staircase railing with 17 steps if the step is 32 cm deep and 14.5 cm high? The last step does not count.
Wall brick count
How many bricks are needed to build a wall that is 12 m long, 1.6 m high, and 47 cm wide if the dimensions of the brick are 30 x 15 x 7.5 cm and 5% of the wall volume is mortar?
Plane sound echo
A plane flying at 612 km/h speed sent a sound signal. In front of the aircraft (in the direction of flight), there is a fixed object at a distance of 3 km, from which the sound is reflected back to the plane. How long will it take the pilot to hear the ec
We randomly
We randomly select a three-digit number. What is the probability that the number 8 occurs at most once in its notation?
Team time percentage
All three team members took turns fulfilling the competition task without delay. The first member used up 30% of the total competition time. The second needed 10 minutes more than the first, and only 10 minutes remained for the third. What % of the total
Triangle tangent area
The tangent of the angle formed by the adjacent sides of the triangle ABC (side a=29 m, b = 40 m) equals 1.05. Calculate the area of that triangle.
Inscribed cube
A cube is inscribed in a sphere with a radius of 27 cm. Calculate its volume and surface area.
House rent tax
From a rented house worth 1.25 million CZK, the owner will receive an annual rent of 6.5% of the house price. 20% tax applies to the rent. How much CZK will the owner have from the rent per year?
Small density cube
Calculate the mass of a cube with an edge of 15 cm made of oak wood with a density of ρ = 800 kg/m³.
Mobile price increase
The mobile was increased by a quarter of the original price and then again by a quarter of the new price. How much did the mobile cost if its final price was 125 euros?
Car consumption average
The car consumes up to 16 l in the city, but on a longer trip, the consumption drops to 10 l? 500 km per month in the city and 1650 km outside the city. What is the consumption of a car per 100 km?
Block volume ratio
The block surface is 5,632 m². The lengths of the edges are in the ratio 1: 2 : 3. Calculate the volume of the cuboid.
Square side increase
We increased the side of the square by 12% from the original 15cm. For a, what was the perimeter and area of the new square? By what percent did the perimeter and area increase?
Prism volume surface
Calculate a prism's volume and surface area with a base of a right triangle with cantilevers of length 40 and 43 cm. The height of the prism is 60 cm.

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