# Examples for 8th grade - page 43

- Round table tablecloth

Round table has area 50.24 dm^{2.}Calculate the diameter of the circular tablecloth, if it is extend beyond the edge of the table by 30 cm. - Square prism

Calculate the volume of a square prism of high 2 dm wherein the base is: rectangle with sides 17 cm and 1.3 dm - Total displacement

Calculate total displacement of the 12-cylinder engine with the diameter of the piston bore B = 6.8 cm and stroke S=2 cm of the piston. Help: the crankshaft makes one revolution while the piston moves from the top of the cylinder to the bottom and back t - Annulus

Two concentric circles form an annulus of width 10 cm. The radius of the smaller circle is 20 cm. Calculate the content area of annulus. - Saw

Imagine that the saw blade with diameter 35 cm has one tooth colored with a different color. How long is path describing by the tip of the tooth after 7 minutes, if the blade is rotated 4704 times? - The dam

The water reservoir is filled with first tributary for 25 hours second tributary for 35 hours. Some time were both inlets open, then a second tributary closed and the tank was filled in four hours. What time water flowed from both tributaries? (Expressed i - Mixing

If we mix 5 kg of goods of one kind and 3 kg second one, resulting mixture cost 16.50 EUR/kg. If these quantities are mixed in reverse - first three kilograms and 5 kilograms second cost of mixture is 18.50 EUR/kg. What is the price of one kg of goods of. - Workers

Ten workers must pave road street for 22 working days. After four days were for speeding up work added two more workers. a) After how many work days now workers completes the paved road? b) How many working days it took a total paved road? - Olympics

In how many ways can be placed 6 athletes on the podium at the Olympics? Depend on the color of the metal. - Aquarium 6

How high is the water level in the aquarium with a rectangular base 40cm and 50cm if it is filled 0,65hl of water? - Machines 2

2 machines for 50 hours produces 2,000 products. How many machines need to buy to make in 30 hours 15,000 products? - Flowerbed

On the flowerbed was planted 310 flowers - pansies and crayons. During the first week wilts quarter of pansies and an eighth crayons, which is 20% of all flowers. How many pansies were planted on the flowerbed? - Midpoint of segment

Point A has coordinates [15; 1] and the midpoint of the segment AB is the point [-20; 13]. What are the coordinates of point B? - Soup

61% of pupils at the school to eat in the canteen, 1/61 of students who eat in the canteen eat lunch soup. a) What percentage of pupils who eat in the canteen and eat soup for lunch? b) What percentage of all pupils of school eat lunch soup? - Chicken and rabbits (classic)

Grandmother breeding chickens and rabbits. It found that the yard has 22 heads and 66 legs. How many chickens and rabbits breeding in the yard? - Czech crown salary

The monthly salary of the employee is CZK 10,800. In the course of the year the bulk salary increased by CZK 500. Calculate which month (1 ... 12) was increased if its annual income was 133,600 CZK. - Two trains

Two trains go at each other. First at speed 40 km/h and the second at speed 60 km/h. At what distance will be 30 minutes before they will meet? - Water level

The glass container has a cuboid shape with dimensions of the bottom 24 cm and 12 cm. The height of water is 36 cm. Calculate the volume of the body, which are sunk into the water if the water level rise by 3 cm. - Cosine

The point (21, 20) is on the terminal side of angle θ. cos θ = ? - Cuboid - simple

Calculate the surface area and volume of a cuboid if a = 8 cm, b = 14 cm and c = 6 cm.

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