# Examples for 8th grade - page 19

- MO - triangles

On the AB and AC sides of the triangle ABC lies successive points E and F, on segment EF lie point D. The EF and BC lines are parallel and is true this ratio FD:DE = AE:EB = 2:1. The area of ABC triangle is 27 hectares and line segments EF, AD, and DB se - Hollow sphere

Steel hollow sphere floats on the water plunged into half its volume. Determine the outer radius of the sphere and wall thickness, if you know that the weight of the sphere is 0.5 kg and density of steel is 7850 kg/m^{3} - Root

Use law of square roots roots: ? - Lock

Combination lock will open when the right choice of 5 numbers (from 1 to 12 inclusive) is selected. A. How many different lock combinations are possible? B. Is he combination lock named appropriately? - Nine-gon

Calculate the perimeter of a regular nonagon (9-gon) inscribed in a circle with a radius 20 cm. - 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. - Event probability

The probability of event G in 9 independent experiments is 0.48. What is the probability that the event G occurs in one experiment (probability is same)? - Intersections

How many intersections have circles with radius 12 dm and 17 dm, if the distance of their centers is 20 dm. - Shots

2000 lead shots with diameter 2 mm is decanted into a ball. What is it diameter? - Dices

We will throw two dice. What is the probability that the ratio between numbers on first and second dice will be 1:2? - Box

Calculate the angle between box base 5 x 7 and body diagonal length 14. - Balance

The rod are 1.7 m long hanging weights 2 kg and 12 kg on ends. Where are centre of rod (distance from weight 2 kg) to be in balance? - Election mathematics

In elections, 6 political parties received this shares of voters: strana A 69.4 %strana B 11.2 %strana C 10.2 %strana D 7.6 %strana E 1.6 % Calculate what the shares acquired in the parliament, if a quorum is 5%. - The bridge

Across the circle lakepasses through its center bridge over the lake. At three different locations on the lake shore are three fishermen A, B, C. Which of fishermen see the bridge under the largest angle? - Do you solve this?

Determine area S of rectangle and length of its sides if its perimeter is 96 cm. - Circumscribing

Determine the radius of the circumscribed circle to the right triangle with legs 3 cm and 3 cm. - 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. - Isosceles III

The base of the isosceles triangle is 24 cm area 416 cm^{2.}Calculate the perimeter of this triangle. - Felix

Calculate how much land saw Felix Baumgartner after jump from 22 km above ground. The radius of the Earth is R = 6378 km. - Christmas Day

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

- «
- 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
- 89
- »

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