# Examples for 8th grade - page 13

1. Percent calculation Calculate 61% if 85% is 38.
2. Rectangles How many rectangles with area 8713 cm2 whose sides is natural numbers are?
3. Estate Semicircle estate must be fence. The straight section has 26 meters long fence. How many meters of fence should buy?
4. n-gon Gabo draw n-gon, which angles are consecutive members of an arithmetic sequence. The smallest angle is 70° biggest 170°. How many sides have Gabo's n-gon?
5. Stairway What angle rising stairway if step height in 17 cm and width 27 cm?
6. Climb Road has climbing 1:27. How big is a angle corresponds to this climbing?
7. Square 2 Points D[10,-8] and B[4,5] are opposed vertices of the square ABCD. Calculate area of the square ABCD.
8. Plan of the village Plan of the municipality in 1:1000 scale has plotted garden with dimensions 25 mm and 28 mm. Determine the area of gardens in ares in reality.
9. Motion From two different locations distant 232 km started against car and bus. The car started at 5:20 with average speed 64 km/h. Bus started at 7:30 with average speed 80 km/h. When they meet? How many kilometers went the bus?
10. Rotary cone Rotary cone whose height is equal to the circumference of the base, has a volume 229 cm3. Calculate the radius of the base circle and height of the cone.
11. Sale If the product twice price cut by 25%, what percentage was price cut in total?
12. Square grid Square grid consists of a square with sides of length 1 cm. Draw in it at least three different patterns such that each had a content of 6 cm2 and circumference 12 cm and that their sides is in square grid.
13. Triangular pyramid Calculate the volume and surface area of a regular triangular pyramid whose height is equal to the length of the base edges 10 cm.
14. 4s pyramid Regular tetrahedral pyramid has a base edge a=17 and collaterally edge length b=32. What is its height?
15. The chord Side of the triangle inscribed in a circle is a chord passing through circle center. What size are the internal angles of a triangle, if one of them is 40°?
16. 2x cone Circular cone height 84 cm was cut plane parallel with base. Volume of these two small cones is the same. Calculate the height of the smaller cone.
17. Circle section Equilateral triangle with side 33 is inscribed circle section whose center is in one of the vertices of the triangle and the arc touches the opposite side. Calculate: a) the length of the arc b) the ratio betewwn the circumference to the circle sector.
18. Unknown x If we add to unknown number 21, then divide by 6 and then subtract 51, we get back an unknown number. What is this unknown number?
19. Trapezoid Are diagonals in a rectangular trapezoid perpendicular and bisect the angles?
20. Inheritance After death father (♱ 62) remained mother (his wife) and its 3 children. Inheritance by law is that in first mother will automatically get half of the property and other one half inherite by heirs witch are mother and her 3 children by same share. Cal

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