# Examples for 8th grade - page 55

1. Regular triangular prism Calculate the surface area of body of regular triangular prism, when the length of its base edge is 6.5 cm and height 0.2 m.
2. Parallelogram ABCD The area of parallelogram ABCD is 440 cm2. Points M and N are the midpoints of the sides AB and BC. What is the area of a quadrilateral MBND?
3. Fraction For what x expression ? equals zero?
4. President The country has 5.11 million citizens which 2.12 million are voters. Turnout was 34.4%. President R. F. was elected from 20 candidates for president and won with 38% of votes. Calculate what percentage of the country's citizens voted R.F. as president o The shadow of the tree is 16 meters long. Shadow of two meters high tourist sign beside standing is 3.2 meters long. What height has tree (in meters)?
6. Bonbons 2 Kilo sweets will cost 260 CZK. The first type has a price per 320 kg, the second type 240 CZK per kg. How many kilos of both kinds of sweets need to prepare a 100 kg mixture ?
7. Chord 4 I need to calculate the circumference of a circle, I know the chord length c=22 cm and the distance from the center d=29 cm chord to the circle. Peter and Franta threw to the basket. Each had 20 attempts. Peter scored thirteen and twelve Franta. Give them success in percentage.
9. Internal and external angles Calculate the remaining internal and external angles of a triangle, if you know the internal angle γ (gamma) = 34 degrees and one external angle is 78 degrees and 40 '. Determine what kind of triangle it is from the size of its angles.
10. The tent The tent shape of a regular quadrilateral pyramid has a base edge length a = 2 m and a height v = 1.8 m. How many m2 of cloth we need to make the tent if we have to add 7% of the seams? How many m3 of air will be in the tent?
11. Tiles How much you will pay CZK for laying tiles in a square room with a diagonal of 8 m if 1 m2 cost CZK 420?
12. Unknown number 5 I think unknown number. If we enlarge it five times then subtract 3 and result decreases by 75% we get the number by one greater than the number I think. What number am I thinking?
13. V - slope The slope of the line whose equation is -3x -9 = 0 is
14. Concentration How 0.5 liters of 8% vinegar diluted to a concentration of 20 hundredths % of vinegar? How many liters of water must be pour?
15. Office Office building was built in the shape of a regular hexagon inscribed in a circle with a radius of 12 m. The height of the walls is 7m. How much CZK cost plastering the walls of the building, if per 1 m square cost CZK 400?
16. Strange x For what x is true ??
17. Isosceles triangle Calculate area and perimeter of an isosceles triangle ABC with base AB if a = 6 cm, c = 7 cm.
18. 3 days Worker checked 2,950 products in 3 days. Second day checked 25% more than the first day. The third day 15% more products than the second day. How many products he checked in each day.
19. Waiting room In the waiting room are people and flies. Together they have 15 heads and 50 legs (fly has 6 legs). How many people and flies are in the waiting room?
20. Price reduction Price of camera is 654 USD on sale its price reduced to 411 USD. Calculate the percentage reduction in the price of the camera.

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