# Examples for 8th grade - page 10

1. Rhombus Find the length of the other diagonal and area of rhombus. The perimeter of a rhombus is 40 cm and one of the diagonals is of length 10 cm.
2. Pizza Pizza with a diameter 50 cm have weight 559 g. What diameter will have a pizza weighing 855 g if it is make from the same cloth (same thickness....) and same decorated?
3. Acid The barrel is 199 litres of 38% acid. How many percent acid occurs when 61 litres revoke and replace it with the same amount of water?
4. Climb On the road sign, which informs the climb is 8.7%. Car goes 5 km along this road. What is the height difference that car went?
5. ISO triangle Calculate the area of an isosceles triangle KLM if the length of its sides are in the ratio k:l:m = 4:4:3 and has perimeter 377 mm.
6. Tape Video is 153% more expensive than tape recorder. How many percent is tape recorder less expensive than video?
7. Triangular prism Plane passing through the edge AB and the center of segmet CC' of regular triangular prism ABCA'B'C', has angle with base 22 degrees, |AB| = 6 cm. Calculate the volume of the prism.
8. Cone Circular cone with height h = 29 dm and base radius r = 3 dm slice plane parallel to the base. Calculate distance of the cone vertex from this plane, if solids have the same volume.
9. Tourists From the cottage started first group of tourists at 10:00 AM at speed 4 km/h. The second started after them 47 minutes later at speed 6 km/h. How long and how many kilometers from the cottage will catch the first group?
10. Garden Father dig up the garden in 9 hours. Son in 13 hours. How many hours take dig up the garden together?
11. Prism Three cubes are glued into prism, sum of the lengths of all its edges is 115 cm. What is the length of one edge of the original cube?
12. Shelf How many ways are there to arrange 6 books on a shelf?
13. Diagonals of the rhombus Calculate height of rhombus whose diagonals are 12 cm and 19 cm.
14. Bicycle wheel A bicycle wheel has a diameter of 60 cm. Approximately how many times does wheel rotate at 2.5 km long trip?
15. Rhombus 2 Calculate the area of rhombus which has a height v=48 mm and shorter diagonal u = 60 mm long.
16. Tower How many m2 of copper plate should be to replace roof of the tower conical shape with diameter 24 m and the angle at the vertex of the axial section is 144°?
17. Profitable bank deposit 2012 Calculate the value of what money lose creditor with a deposit € 9500 for 4 years if the entire duration are interest 2.6% p.a. and tax on interest is 19% and annual inflation is 3.7% (Calculate what you will lose if you leave money lying idle at negative
18. Cube The cube weighs 11 kg. How weight is cube of the same material, if its dimensions are 3-times smaller?
19. Equilateral triangle How long should be the minimum radius of the circular plate to be cut equilateral triangle with side 19 cm from it?
20. Hexagon A Calculate area of regular hexagon inscribed in circle with radius r=9 cm.

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