Math practice for 13 year olds - page 72 of 413
Number of problems found: 8260
- 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 a station at a speed of 75 km/h. At 10:00 AM, 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) At wh - 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 15 cm. 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. - Block surface ratio The volume of the block is 7,500 dm³. The lengths of the edges are in the ratio 3: 4: 5. Calculate the surface area of the cuboid.
- Cuboid surface ratio The volume of the cuboid is 960 cm³. The lengths of the edges are in the ratio 1 : 3: 5. Calculate the surface area of the cuboid.
- Ball box percentage
A ball with a diameter of 10 cm is in a cube-shaped box with an edge of 10 cm. What percentage of the box does the ball fill?
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