# Examples for 8th grade - page 57

1. Mr. Vojta Mr. Vojta put in the bank 35000 Kč.After a year bank him credited with interest rate of 2% of the deposit amount. How then will Mr. Vojta in the bank?
2. Sugar cubes The glass has 600 ml of tea, which represents 80% of the volume of the glass. If you put twenty regular sugar cubes of 2 cm in the tea, how many ml of tea are poured?
3. Cuboid - volume, diagonals The length of the one base edge of cuboid a is 3 cm. Body diagonal is ut=13 cm and diagonal of cuboid's baseis u1=5 cm. What is the volume of the cuboid?
4. Tank 9 The tank with volume V is filled with one pump for three hours and by second pump for 5 hours. When both pumps will run simultaneously calculate: a) how much of the total volume of the tank is filled in one hour b) for how long is the tank full
5. Cube 9 What was the original edge length of the cube if after cutting 39 small cubes with an edge length 2 dm left 200 dm3?
6. ABS What is the value of ? ?
7. Cube volume The cube has a surface of 384 cm2. Calculate its volume.
8. Areaf of ST It is given square DBLK with side |BL|=13. Calculate area of triangle DKU if vertex U lie on line LB.
9. Painting school Redecoration school had scheduled for four crew to 10 days. After two days a single worker ill. For how many days the school was painted when remain workers working with the same tempo?
10. Slope form Find the equation of a line given the point X(8, 1) and slope -2.8. Arrange your answer in the form y = ax + b, where a, b are the constants.
11. Square - increased perimeter How many times is increased perimeter of the square, where its sides increases by 150%? If the perimeter of square will increase twice, how much% increases the content area of the square?
12. Classs mean Class size is 30 students, math was not worse than sign 2. Determine the number of pupils who were sign 1 if the class had a 1.4 sign average.
13. Holiday SMS Kucera and Malek start from the holiday together. They agreed that if they be 100 km apart, will send a SMS. Kucera traveling at 60 km/h., Malek 90 km/h. They started at 14 hours PM. At what time they send a message?
14. Rope slack Between two streets 20 m away give the lamp, which is in the middle and hanging 60 cm bellow the taut rope. Can be done with 20.5 meters rope?
15. 6-gon Perimeter of regular hexagon is 113. Calculate its circumradius (radius of circumscribed circle).
16. Triangle eq Calculate accurate to hundredths cm height of an equilateral triangle with a side length 12 cm. Calculate also its perimeter and content area.
17. Copy typist Typist for 12 hours rewritten 15% of the manuscript. After how many hours he will done 35% of the manuscript?
18. Seven tractors Seven tractor plowed 308 ha field in four days. How many hectares of fields will plowe 9 tractors in 3 days at the same power?
19. Rhombus and diagonals The a rhombus area is 150 cm2 and the ratio of the diagonals is 3:4. Calculate the length of its height.
20. Washing machine The price of washing machine was decreased by 21% and then by 55 € due small sales. After two price decreases cost € 343. How much was originally cost?

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