# Examples for 8th grade - page 20

- Count of roots

How many solutions has equation x. y = 2531 with two unknowns on the set of natural numbers? - Similarity n-gon

11-gones ABCDEFGHIJK and A'B'C'D'E'F'G'H'I'J'K' are similar. The area of 11-gon ABCDEFGHIJK is S_{1}=254 cm^{2}and the diagonal length HG is 20 cm. Calculate area of the 11-gon A'B'C'D'E'F'G'H'I'J'K' if H'G' = 36 cm. - Cone in cylinder

The cylinder is inscribed cone. Determine the ratio of the volume of cone and cylinder. The ratio express as a decimal number and as percentage. - Two balls

Two balls, one 8cm in radius and the other 6cm in radius, are placed in a cylindrical plastic container 10cm in radius. Find the volume of water necessary to cover them. - Dog

Man goes with a dog on a long walk 18 km from the house. Man is walking at speed 5.3 km/h and a dog that constantly running between house and man at 17.1 km/h. How many kilometers will run the dog when they reach their destination? - Christmas Day

In leap years was 53 Sundays. On what day of the week fell to Christmas Day? - Rhombus HP

Calculate area of the rhombus with height 98 mm and perimeter 20 mm. - Insurance

The owner of the house is insured against natural disasters and pays 0.04% annually of the value of house 103 Eur. Calculate the value of the house. Calculate the probability of disaster, if you know that 42% of the insurance is to pay damages. - Workers

Workers digging a jump pit in the school yard. Pit has a cuboid shape with a length 20 m, a width 20 dm and depth 36 cm. They excavate 0.4 cubic meters of soil an hour. How much time (hours and minutes) is need to the excavate this pit? - Reservoir + water

Reservoir completely filled with water weighs 13 kg. After pouring off three quarters of the amount of water weights 4 kg. Calculate the weight and volume of the reservoir. - Height

Calculate height of the equilateral triangle if its perimeter is 54? - Electronics: Resistors in parallel

From relation for calculating the resistance of parallel combination of resistors: ? Calculate the R, if R_{1}= 8kΩ a R_{2}= 18kΩ - Sector

The perimeter of a circular sector with an angle 2 rad is 53 cm. Determine the radius of the circle from which the sector comes. - Degrees to radians

Convert magnitude of the angle α = 618°40'29" to radians: - Concrete pipe

Concrete pipe is cylindrical with an inner diameter 130 cm and outer 142 cm. Calculate the surface of the concrete pipe, if it is 6 m long. - Horizon

The top of a lighthouse is 12 m above the sea. How far away is an object which is just “on the horizon”? [Assume the earth is a sphere of radius 6378.1 km.] - Circles

Area of circle inscribed in a square is 6. What is the area of a circle circumscribed around a square? - Cathethus and the inscribed circle

In a right triangle is given one cathethus long 14 cm and the radius of the inscribed circle of 5 cm. Calculate the area of this right triangle. - Task

I have homework. The cube has an edge 11 cm long and I must find wall and body diagonal. - Salary

Clerk got to pay 1200 Euros in banknotes of 50 and 200 Eur. Total got 9 banknotes. How many was which?

- «
- 1
- 2
- 3
- 4
- 5
- 6
- 7
- 8
- 9
- 10
- 11
- 12
- 13
- 14
- 15
- 16
- 17
- 18
- 19
- 20
- 21
- 22
- 23
- 24
- 25
- 26
- 27
- 28
- 29
- 30
- 31
- 32
- 33
- 34
- 35
- 36
- 37
- 38
- 39
- 40
- 41
- 42
- 43
- 44
- 45
- 46
- 47
- 48
- 49
- 50
- 51
- 52
- 53
- 54
- 55
- 56
- 57
- 58
- 59
- 60
- 61
- 62
- 63
- 64
- 65
- 66
- 67
- 68
- 69
- 70
- 71
- 72
- 73
- 74
- 75
- 76
- 77
- 78
- 79
- 80
- 81
- 82
- 83
- 84
- 85
- 86
- 87
- 88
- »

Do you have interesting mathematical example that you can't solve it? Enter it and we can try to solve it.