Maths practice for 12-year-olds - page 327 of 362
Number of problems found: 7223
- Rectangle and circle
The rectangle ABCD has side lengths a = 40 mm and b = 30 mm and is circumscribed by a circle k. Calculate approximately how many centimeters a circle is long. - The star
Find the area of the shaded part of the square with a side of 22 cm. - Clocks
What distance will describe the tip of a minute hand 6 cm long for 20 minutes when we know the starting position with finally enclosed hands at each other at 120°? - Annulus
Two concentric circles form an annulus with a width of 10 cm. The radius of the smaller circle is 20 cm. Calculate the area of the annulus. - Arc
What area of a circle occupied the flowers planted in the arc of a circle with a radius 3 m with a central angle of 45°? - Two circles
Two circles with a radius of 4 cm and 3 cm have a center distance of 0.5cm. How many common points have these circles? - 22/7 circle
Calculate approximately the area of a circle with a radius 12 cm. When calculating π, use 22/7.
- Plums
The bag contained a total of 136 plums. Igor took 3 plums, and Mary took 4/7 from the rest. Thus, how many plums remained in the bag? - Janitor
The janitor tosses 26 cm layer of snow on the school grounds for 90 minutes. How many friends would have to call for help if snow needs to have bowled for 15 minutes? We assume that at the same time, we all have the same amount of snow. - Troops - soldiers
Food stocks will last 20 soldiers during the four-day training. If four soldiers become sick, how many days could they extend training? - Pumps 3
Two pumps of the same power fill the garden pool for 10 hours. How many of these pumps would we have to use if we want to shorten the filling of the pool to four hours? - Supermarket cashiers
When only two checkouts are open in a supermarket, people wait in line for an average of 12 minutes. If three more ticket offices are opened, how much will the average waiting time in line be reduced? - Hurry - rush
I will travel from the school to the bus stop at an average speed of 7 km/h for 30 minutes. How fast do I need to go if I need to get there in 21 minutes? - Floating floor
In the new building, a floating floor worker is considered in each room. Thirty minutes lay 9 m² of the floor. How long did three workers lay the floor in four rooms with a total area of 90 m²? - Building base
Excavation for the building base is 350x600x26000. Calculate its volume in m³.
- The rod
The rod is painted in four colors. 55% of the bar is painted blue or green, 0.2 of the rod, 1/8 is brown, and the remaining 45 cm is white. How long is the rod? - Concrete pipe
How much will it cost to cover a 6 m long concrete pipe with an outer radius of 1.5 m and an inner radius of 0.8 meters if one m² paint costs 24 €? - Jam cakes
Mom baked a third of plum jam cakes, one-third of cheesecakes, and 18 poppy. How many cakes she had bake? - For thinkings
The glass cube dives into the aquarium, which has a length of 25 cm, a width of 20 cm, and a height of 30 cm. Aquarium water rises by 2 cm. a) What is the volume of a cube? b) How many centimeters measure its edge? - Concrete tank
How many m³ of concrete is in the tank shape of a cuboid with dimensions of 2000 cm and, 5.6 meters, and 70 dm if the concrete takes up 3/7 of the tank?
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