Maths practice for 12-year-olds - page 358 of 362
Number of problems found: 7228
- Box
Calculate the angle between box base 9 x 14 and body diagonal length 18. - Observatory
The observatory dome has the shape of a hemisphere with a diameter d = 10 m. Calculate the surface. - Rotating cone II
Calculate the area of the surface of a rotating cone with base radius r=15 cm and height h=13 cm. - Rotating cone Calculate the volume of a rotating cone with base radius r=18 cm and height h=20 cm.
- Is right?
Is a triangle with sides 15, 66, and 68 right triangle? - Average
The average of 5 numbers is 108. What is its sum? - Bulbs
In the box are 6 bulbs with power 75 W, 14 bulbs with power 40 W, and 15 with 60 W. Calculate the probability that a randomly selected bulb is:
- Rectangles
How many rectangles with area 8855 cm² whose sides are natural numbers? - Minute angle
Find the size of the angle, which takes a minute hand for 30 minutes. - Guess number
With what number should be divided, number 9727 to be reduced by 70%? - Secret number
Find the secret number n, which reversed decreases by 16.4 if the number increases by 16.4. - Clock
How long is the trajectory of the second hand of hours for day, if it is 15 mm long? - Earth parallel
Earth's radius is 6377 km long. Calculate the length parallel to latitude 75°. - Tree trunk
Calculate the average tree trunk with a circumference of 192 cm. - Seedcake
Seedcake costs 44 cents. How many minimum seedcakes must we buy that we can pay in cash, only whole euros?
- Equilateral triangle
Calculate the side of an equilateral triangle if its area is 886 mm². - Circle
How big is the area of a circle if its circumference is 51.2 cm? - Truncated cone
Calculate the volume of a truncated cone with base radiuses r1=19 cm, r2 = 11 cm, and height v = 5 cm. - DIY press
Under the socialist regime, in some socialist countries, owning a typewriter required special permission. That has hindered the spread of DIY literature (manually transcribed through carbon copy paper for typewriters). Calculate how many typewriters today - Copper sheet
The copper plate has a length of 2.2 m, width 92 cm, and weighs 5.6 kg. What is the plate thickness if 1 m³ weighs 8732 kg?
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