# Examples for 8th grade - page 63

1. Isosceles right triangle
Contents of an isosceles right triangle is 18 dm2. Calculate the length of its base.
2. 3 years
The company has increased the number of employees. In year 2005 compared to 2004 13% more, in 2006 18% more against the previous year, in year 2007 20% more compared to 2006. How many % increase in the number of employees in 3 years?
3. Wheel
Diameter of motocycle wheel is 52 cm. How many times rotates wheel on roand long 2 km?
4. Tripled square
If you tripled the length of the sides of the square ABCD you increases its content by 200 cm2. How long is the side of the square ABCD?
5. Probability - tickets
What is the probability that when you have 25 tickets in 5000 that you wins the first (one) prize?
6. Ethnicity
Share of ethnicity XY is 26%, which is 1/9 more than in the prewar period. What was the share of that ethnicity in the pre-war period?
7. Pyramid 4sides
Calculate the volume and the surface of a regular quadrangular pyramid when the edge of the base is 4 cm long and the height of the pyramid is 7 cm.
8. Runners circle
Pepa circles the track in 36 seconds. Kamil in 42 seconds. They started together. How many seconds will meet again at the start?
9. Chord 5
It is given circle k / S; 5 cm /. Its chord MN is 3 cm away from the center of the circle . Calculate its length.
10. Right triangle
It is given a right triangle angle alpha of 90 degrees beta angle of 55 degrees c = 10 cm use Pythagorean theorem to calculate sides a and b
11. Percent chaining
Calculate 20% from 70% from 80 km
12. Prism
Find the volume and surface area of prism with base of an equilateral triangle with side 7 dm long and the body height of 1.5 m.
13. Farm2
The farm bred turkeys, geese, hens and chickens. Everything is 400. Turkeys and geese a hen are 150. No hen has more than one chicken, but some hens has no chick. Half of them is also a quarter of the chickens. When the turkey subtracting 15, we get 75. Ho
14. Tiles
How many square tiles with the content 121 cm2 has to be ordered for the paving of the square room with a side length of 2.75 meters?
15. 4 pipes
The tank flows out by 4 pipes in 6 hours 120 hl water. How much water flows out of 5 pipes of the same diameter in 14 hours?
16. Two rooms
Woman cleans the room in 30 minutes a man in 90 minutes. How long will take they clean two rooms?
17. Coal
If the daily consumption of 1.6 tons of coal, it is sufficient to supply the boiler for 42 days. How long is sufficient to supply when will burn only 1.2 tons of coal a day ?
18. Algebrogram
Solve algebrogram: mama+anna=vari How many solutions are?
19. Mother and daughter
The ratio of years mother and daughter is 5:2. After 7 years the ratio is 2: 1. How many years ago daughter was born?
20. Double percent
What is 80% of 60% of 2800?

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