Math practice for 13 year olds - page 408 of 413
Number of problems found: 8253
- Gear wheels
Two meshing gear wheels have tooth counts of z₁ = 43 and z₂ = 154. Calculate the speed of the first wheel if the second wheel rotates at 766 revolutions per minute. - Median
In the right triangle are sides a=96 dm b=31 dm. Calculate the length of the medians tc to the hypotenuse. - Rectangles
How many rectangles with an area of 8855 cm² have sides that are natural numbers? - Secret number
Find the secret number n, which reversed decreases by 15.4 if the number increases by 15.4. - Seedcake
Seedcake costs 20 cents. How many minimum seedcakes must we buy that we can pay in cash, only whole euros? - Conserving water
Calculate how many euros are spent annually on unnecessary domestic hot water, which cools during the night in the pipeline. The residential house has 223 m of hot water pipelines 1" and the hot water has a price of 14.6 Eur/m³. - Triangle
Calculate all three altitudes of triangle ABC with sides a = 26, b = 81, and c = 73. - Diamond
Find the side length of a rhombus whose area is S = 194 cm² and one diagonal is u₂ = 44 cm. - Lead cube
Calculate the cube's edge made from lead, which weighs 14 kg. The density of lead is 11341 kg/m³. - Pump
What power output must a pump have to raise 1060 hl of water to a height of 43 m in 8 hours? - The cap
A jester's hat is in the shape of a cone. Calculate how much paper is needed to make a hat 53 cm tall for a head circumference of 45 cm. - Chord MN
Chord MN of a circle has a distance of 28 cm from the centre S. Angle MSN is 54°. Determine the radius of the circle. - Car range
Kia has an average diesel consumption of 5.2 liters per 100 kilometers. What is the range of the car for 138 euros if fuel costs 1.3 EUR/liter, if the tank has a volume of 64 liters? - Median
In triangle NOP, the centroid is 95 cm from vertex P. Calculate the length of the median from vertex P. - Event probability
The probability of event N in 5 independent experiments is 0.4. What is the probability that the event N occurs in one experiment (chance is the same)? - Flags
How many different flags can be made from green, white, blue, red, orange, yellow, and purple materials if each flag consists of three stripes of different colours? - Carbon dioxide
Calculate how many grams of oxygen are in 59 grams of carbon dioxide CO2. The relative atomic mass of oxygen is 16, and of carbon is 12. - Isosceles right triangle
Calculate the area of an isosceles right triangle whose perimeter is 810 cm. - Air mass
What is the mass of the air in a classroom with dimensions 10 m × 3 m × 3 m? The density of air is 1.293 kg/m³. - Barrel of oil
The barrel of oil weighs 283 kg. When it molded 26% oil, it weighed 216 kg. What is the mass of the empty barrel?
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