# Examples for 8th grade - page 111

1. Half-sphere roof The roof above the castle tower has the shape of a 12.8 m diameter half-sphere. What is the cost of this roof, if the cost of 1 square meter is 12 euros and 40 cents?
2. A boy A boy of height 1.7m is standing 30m away from flag staff on the same level ground . He observes that the angle of deviation of the top of flag staff is 30 degree. Calculate the height of flag staff.
3. Girls The children's competition was attended by 63 girls, which is 30% of all children's participants. How many children attended this competition?
4. Area to volume If the surface area of a cube is 486, find its volume.
5. Ratio of sides Calculate the area of a circle that has the same circumference as the circumference of the rectangle inscribed with a circle with a radius of r 9 cm so that its sides are in ratio 2 to 7.
6. Coins The boy collected coins with value 5 CZK and 2 CZK when he had 50 pieces saved 190 CZK. How many he has each type of coin?
7. T-shirts and hat 5 t-shirts and a hat cost £62.00 2 t-shirts and a hat cost £29.00 How much does a t-shirt cost ? How much does a hat cost ?
8. Isosceles triangle In an isosceles triangle, the length of the arm and the length of the base are in ration 3 to 5. What is the length of the arm?
9. Tickets 1260 tickets sold. On the first day, 80% was sold on the second day was sold. How many tickets were sold first and how much the next day?
10. Coordinates of midpoint If the midpoint of the segment is (6,3) and the other end is (8,4) what are the coordinate of the other end?
11. Ditch Ditch profile is an isosceles trapezoid with bases of length 80m and 60m. The slope of the side wall of the ditch is 80°. Calculate the ditch depth.
12. The garden The garden has the shape of a rectangular trapezium. The bases have lengths of 27 meters and 36 meters, the trapezoid's height is 12 meters. Calculate how much fence will cost this garden if one meter costs 1.5 €?
13. Drying herbs Herbs lose 75% weight By drying. How many fresh herbs do you have to collect if you want to make 1.5 kg of dried herbs?
14. Ebay is not free Be aware of ebay - if you sell something expensive, fee is painful. There are lot of space for classifieds and local exchange away from global ebay. Calculate ebay+paypal fee if you sale 3037 USD laptop. Formula for ebay fee is 0,30 + 10 % of total earning
15. Hotel rooms In the 45 rooms, there were 169 guests, some rooms were three-bedrooms and some five-bedrooms. How many rooms were?
16. Solve 2 Solve integer equation: a +b+c =30 a, b, c = can be odd natural number from this set (1,3,5,7,9,11,13,15)
17. The truck The empty truck left the warehouse for goods at 10:00 and arrived at 11:30. At 2:00 pm, they loaded back on the same route. But it was a quarter slower than going to the warehouse. We know that on the way to the warehouse, the car was traveling at a speed.
18. Paper box Calculate how much we'll pay for a three-side shaped prism box with a triangular base, and if it measures 12cm and 1.6dm, the hypotenuse measures 200mm. The box is 34cm high. We pay 0,13 € per square meter of paper.
19. Find the 9 Find the missing angle in the triangle and then name triangle. Angles are: 95, 2x+15, x+3
20. Peter and Paul Peter and Paul together have 26 years. Four years ago, Paul was twice older than Peter. How much is Paul and how much Peter?

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