# Examples for 8th grade - page 54

- Outer contact of circles

Construct a circle k1 (S1; 1.5 cm), k2 (S2; 2 cm), and K3 (S3; 2.5 cm) so that they are always two outer contact. Calculate the perimeter of the triangle S_{1}S_{2}S_{3}. - Barrel 4

Barrel of water weighs 63 kg. After off 75% water, the weight of the barrel with water is 21 kg. How many kg weigh empty barrel and how many kgs water in it? - Savings and retirement

The older sibling has saved 44% more euros than the youngest, which represents 22 euros. How many euros older brother has saved ? - The dam

The water reservoir is filled with first tributary for 25 hours second tributary for 35 hours. Some time were both inlets open, then a second tributary closed and the tank was filled in four hours. What time water flowed from both tributaries? (Expressed i - Reciprocal equation

Determine the root of the equation: 9/x-7/x=1 - Right triangles

How many right triangles we can construct from line segments 3,4,5,6,8,10,12,13,15,17 cm long? (Do not forget to the triangle inequality). - Drainage channel

The cross section of the drainage channel is an isosceles trapezoid whose bases have a length of 1.80 m, 0.90 m and arm has length 0.60 meters. Calculate the depth of the channel. - Cableway

Cableway has a length of 1800 m. The horizontal distance between the upper and lower cable car station is 1600 m. Calculate how much meters altitude is higher upper station than the base station. - Great Wall of China

Great Wall of China is long 8880 km. Historically valuable however is only 30% of its length. What amount of insurance pays the Peoples Republic of China a month for this monument, if the insurance company charges $ 10 per year per kilometer of historic s - Rectangle

The rectangle is 18 cm long and 10 cm wide. Determine the diameter of the circle circumscribed to rectangle. - Coffee shop

To the coffee shop brought 2 types of coffee totally 50 kg. The first type was CZK 220 per kilogram, coffee second type 300 CZK per 1 kg. For all the coffee trader earned CZK 12,000. How many kilograms of coffee of first type and how many kilograms of cof - Area of the cone

Calculate the surface area of the cone, you know the base diameter 25 cm and a height 40 cm. - Equilateral triangle v2

Equilateral triangle has a perimeter 36 dm. What is its area? - Circle - simple

Calculate the area of a circle in dm^{2,}if its circumference is 31.4 cm. - Peppers

In the box are yellow (a), green (b) and red (c) peppers. Their amount is in a ratio 2:4:1 . Most are yellow peppers and green the least. Calculate the number of peppers each type if the total number of peppers is 77. - Farm2

The farm bred turkeys, geese, hens and chickens. Everything is 400. Turkeys and geese a hen are 150. No hen has more than one chicken, but some hens has no chick. Half of them is also a quarter of the chickens. When the turkey subtracting 15, we get 75. Ho - Tiles

How many square tiles with the content 121 cm^{2}has to be ordered for the paving of the square room with a side length of 2.75 meters? - Square garden

On the plan with a scale of 1:1500 is drawn as a square garden with area 4 cm^{2.}How many meters is long garden fence? Determine the actual acreage gardens. - Three co-owners

The three co-owners of building company have earnings from a contract portioned in the ratio of 3:6:7. Each of them received the amount in whole USD. One of them on contract earned 86450 USD. What was the total earnings this order? - Jane

Jane buy gift together for 464 Sk. For tie paid 4.5 times less than in the shirt, but 56 Sk more than for socks. How much she paid for each item in gift?

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