Maths practice for 12-year-olds - page 63 of 355

Number of problems found: 7087

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
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.
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?
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.
Horse oats consumption
Three horses will eat 36 kg of oats in two days. How many kilograms do 5 horses need for 4 days? Help yourself by adding or subtracting.
Karel Ondra pursuit
Karel went for a walk at a speed of 5 km/h. After 3 hours, Ondra rode to him with an important message. He was moving at a speed of 20 km/h. How many minutes did Ondra catch up with Karel?
Margaret savings gifts
Margaret bought Christmas presents with a quarter of her savings. How much did she save if the gifts cost CZK 160? Express the rest of the savings as a fraction.
Mercury density measurement
10 ml of mercury has been measured to weigh 0.135 kg. Calculate the density of mercury and compare it with the density shown in the tables.
Multiple smaller nearest
Write the nearest smaller multiple: number 7 to number 23 number 5 to number 19 number 6 to number 23 number 10 to number 79 number 6 to number 41 number 3 to number 28
Tin body mass
The tin body transferred 150,000 J of heat, and its temperature dropped by 10°C. Calculate the mass of the tin body. (c of tin is 0.227 kJ/kg. °C). Enter the resulting weight in grams and round it to two decimal places.
Rhombus construction sides
Construct a rhombus that has a side length of 5 cm and a height of 4.5 cm. Outline: Analysis: Construction: Method:
Ropeway angle length
The ropeway climbs at an angle of 22°30'. Calculate its length if the height difference between the lower and upper station is 560m. Sketch a picture
Castle painting cans
The castle has a length of 4 m and a cross-section in the shape of a square whose side is 15 cm long. Eight such castles must be painted. One kilogram can is enough for 6 m² of coating. How many cans of paint should be bought?
Makarska riviera
The motor boat departs from Baška Voda at 19:15 and arrives in Makarska at an average speed of 30 km/h at 20:00. However, a group of tourists from Germany must be in Makarska a third of the time earlier. What should the average speed of the boat be?
Pump tank emptying
Three identical pumps empty the tank in 1.8 hours. How long will it take 5 pumps to empty this tank?
Ring gold volume
The ring weighs 28g and has a volume of 2cm³ to find out if it is made of pure gold.
Martin age years
Martin will be twice as old in 10 years as he was four years ago. How old is she now?
Cuboid cone volume
We used the same amount of paint to paint a cuboid with dimensions of 10 cm, 15 cm, and 3 cm to paint the shell of a cone whose radius is 8 cm. How tall is this cone? Calculate its volume in liters.
Tablecloth table size
A square tablecloth measures 80 cm so that it protrudes 33 cm on the sides; calculate how big it is.

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