Maths practice for 12-year-olds - page 343 of 347

Number of problems found: 6931

Aircraft
Flight length 2886 km took 4 hours. The airport passengers had to arrive hours in advance, 2 hours. Departure was delayed for 2.3 hours. The destination airport formalities took 0.5 hours. Calculate the average speed of passenger travel from arrival to le
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 longest fishing rod that can be placed in a car boot with dimensions 152 × 82 × 81 cm.
Box
Calculate the angle between the base of a cuboid with dimensions 5 × 10 and its space diagonal of length 13.
Observatory
An observatory dome has the shape of a hemisphere with diameter d = 10 m. Calculate its surface area.
Rotating cone II
Calculate the lateral surface area of a cone with base radius r = 20 cm and height h = 10 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 a right triangle?
Average
The average of 5 numbers is 108. What is their sum?
Rectangles
How many rectangles with an area of 8855 cm² have sides that are natural numbers?
Minute angle
Find the angle swept by the minute hand of a clock in 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 far does the tip of a clock's second hand travel in day, if the second hand is 15 mm long?
Earth parallel
The Earth's radius is 6377 km. Calculate the circumference of the parallel at latitude 75°.
Tree trunk
Calculate the average diameter of a tree trunk whose circumference is 192 cm.
Train
A train travels a section of line in 55 minutes at a speed of 70 km/h. At what speed would it need to travel to shorten the journey time by 16 minutes?
Seedcake
Seedcake costs 20 cents. How many minimum seedcakes must we buy that we can pay in cash, only whole euros?

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