Maths practice for 12-year-olds - page 322 of 351
Number of problems found: 7011
- 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°? - 22/7 circle
Calculate approximately the area of a circle with a radius 12 cm. When calculating π, use 22/7. - 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? - 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 24 minutes. How fast do I need to go if I need to get there in 17 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? - 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? - Peppers
In the box are yellow (a), green (b), and red (c) peppers. Their amount is in a ratio of 2:4:1. Most are yellow peppers and green the least. Calculate the peppers for each type if the total number is 70. - Gloves
I have a box with two hundred pieces of gloves in total, split into ten parcels of twenty pieces, and I sell three parcels. What percent of the total amount I sold? - Rape
The agricultural cooperative harvested 525 ares of rape, of which received 5.6 tons of rape seeds. Calculate the yield per hectare of rape. - 3 years
The company has increased the number of employees. In year 2005 compared to 2004 13% more, in 2006 18% more against the previous year, in year 2007 20% more compared to 2006. How much percent increase in the number of employees in 3 years? - Toys
The toy shop sold the same number of balls for 62 CZK and skipping ropes for 34 CZK. Their income was 576 CZK. How many sold balls, and how many skipping ropes? - BMI index
Calculate BMI (body mass index, an index indicating obesity, overweight, normal weight, underweight) man weighing m = 85 kg and height h = 152 cm. The index is calculated according to the equation (formula): BMI = (m)/(h²) With the BMI index, it is possib
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