Maths practice for 12-year-olds - page 348 of 352

Number of problems found: 7031

Number
Is number 2.8814789 irrational?
Ratio v2
Decrease in the ratio 8:16 number 20.2.
Ratio
Increase the number 25.6 in the ratio 7:4.
Trunk
Calculate the length of the biggest fishing rod that can be inserted into the trunk of a car with dimensions 152 x 82 × 81 cm.
Box
Calculate the angle between box base 5 x 10 and body diagonal length 13.
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?
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 10387 to be reduced by 30%?
Secret number
Find the secret number n, which reversed decreases by 15.4 if the number increases by 15.4.
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.
Train
The train passes part of the line for 55 minutes at a speed of 70 km/h. What speed would you have to go to shorten the driving time of 16 minutes?
Seedcake
Seedcake costs 20 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.

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