# Examples for 8th grade - page 109

1. Grandfather and grandmother The old mother is 5 years younger than the old father. Together they are 153 years old. How many years has each of them?
2. Two trains There were 159 freight wagons on the railway station creating 2 trains. One had 15 more wagons than the other. How many wagons did each train have?
3. Distance of lines Find the distance of lines AE, CG in cuboid ABCDEFGH, if given | AB | = 3cm, | AD | = 2 cm, | AE | = 4cm
4. Scientific notation Approximately 7.5x105 gallons of water flow over a waterfall each second. There are 8.6x104 seconds in 1 day. Select the approximate number of gallons of water that flow over the waterfall in 1 day.
5. Bulb A 60 W bulb consumes 0.12 kWh of electricity. How long did she stand light without a break?
6. Substitution solve equations by substitution: x+y= 11 y=5x-25
7. Complementary angles 2 Two complementary angles are (x+4) and (2x - 7) find the value of x
8. Two masters The two masters will make as many parts as five apprentices at the same time. An eight-hour shift begins at 6 o'clock. When can a master finish the job to produce just as much as an apprentice for the whole shift?
9. Iron pole The iron pole is in the ground 2/5 of its length, partly above the ground 1/3 is yellow, and the unpainted section is 6 m long. How long is the entire column?
10. Sss triangle Calculate the area and heights in the triangle ABC by sides a = 8cm, b = 11cm, c = 12cm
11. Stamps 2 Dennis spent 34.15 on stamps. The number of .56 is 10 less than four times of stamps bought for .41. How many of each stamp did he buy?
12. A pipe A radius of a cylindrical pipe is 2 ft. If the pipe is 17 ft long, what is its volume?
13. A box A box is 15 centimeters long, 4 centimeters wide, and 3 centimeters tall what is the diagonal S of the bottom side? What is the length of the body diagnol R?
14. Playing How long have we trained on the pitch when we know that the warm-up took 10 minutes, we trained passes for one-third of the time and we played football half the time?
15. Two municipalities The horizontal distance between municipalities is 39 km. Average sinking is 7 per mille. What is the difference in height between these municipalities?
16. Diamond and diagonals A diamond has diagonals f = 8 cm and g = 6 cm long. How long is this diamond perimeter? (Calculate it!)
17. Square metal sheet Four squares of 300 mm side were cut out from a square sheet metal plate with a side of 0,7 m. Express the fraction and the percentage of waste from the square metal sheet. Marie wants to make a cone-shaped witch's hat for a masquerade ball. How much material will it need if it counts on an annular rim with diameters of 28cm and 44cm? Hat side length is 30cm. Add 5% of the material to the bust. Round to cm2. The castle tower has a cone-shaped roof with a diameter of 10 meters and a height of 8 meters. Calculate how much m² of coverage is needed to cover it if we must add one-third for the overlap. On Monday, 33 tickets were sold. Every next day, twice as many as the previous day. How many tickets were sold on Friday and how many totally from Monday to Friday?