# Examples for 8th grade - page 62

- 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. - Brigade

On a weekly forest brigade operates 12 students. After plant one hundred spruces get x CZK, anfter one hundred pines y CZK. How many CZK got one student for one day if planted spruces 25000 and 30000 pines week? - Eight blocks

Dana had the task to save the eight blocks of these rules: 1. Between two red cubes must be a different color. 2. Between two blue must be two different colors. 3. Between two green must be three different colors. 4. Between two yellow blocks must be four - Ethernet cez ulicu

Karol a Jozef sú vášniví hráči počítačových hier a býva v domoch, ktoré sú presne naproti sebe cez ulicu, takže si vidia navzájom do okien. Rozhodli sa, že si svoje počítače prepoja telefónnym káblom aby mohli hrať spoločne hry. Karol býva v prvom poschodí - Addends

Number 118 divide into two addends, so first addend is 69 greater than 75% of the second addend. - Mr. Happy

Mr. Happy planted 36.6 meters square gardens grass; It's a third of the garden more than half of the garden. What is square area of this garden? - Forces

Determine the resultant of two perpendicular forces F_{1}= 560 N and second force of 25% smaller. - The pot

Diameter of the pot 38 cm. The height is 30 cm. How many liters of water can fit in the pot? - Sweets

3 chocolate and 7 cakes cost 85, - CZK. 2 chocolates and 6 cakes cost 86, - CZK. How much is 5 chocolates and 9 cakes? I wonder how to get the result, but only by logic without the use of a system of equations - Bricks

Openings in perforated bricks occupy 10% and brick has dimensions 30 cm, 15 cm and 7.5 cm. Calculate a) the weight of a perforated bricks, if you know that the density of the full brick material is p = 1800 kg/m^{3}(1.8 kg/dm^{3}) b) the number of perforated. - Chimney

Lower circumference of of the chimney is 12.57 m, top circumference is 5.655 m. The slope of the walls is 87°. Determine the height of the chimney. - Cube from sphere

What largest surface area (in cm^{2}) can have a cube that was cut out of a sphere with radius 3 cm? - Clock

What distance will pass end of 8 cm long hour hand for 15 minutes? - Annulus

Calculate the area of two circles annulus k_{1}(S, 3 cm) and k_{2}(S, 5 cm). - Sidewalk

The city park is a circular bed of flowers with a diameter of 8 meters, around it the whole length is 1 meter wide sidewalk . What is the sidewalk area? - Unknown number

Samuel wrote unknown number. Then he had add 200000 to the number and the result multiply by three. When it calculated he was surprised, because the result would have received anyway, if write digit to the end of original number. Find unknown number. - Shop stores

Workers untied fruit to stores. In the first quarter shipments, in the second fifth shipment, in the third two-fifths of the rest and in the fourth 231 kilograms. How many fruits were together? - Dollars

Mama split 760 dollars Jane, Dane and Eva as follows: Jane got three times more than Dane and Dane and got 40 more than Eva. How much does get each of them? - Two boxes-cubes

Two boxes cube with edges a=74 cm and b = 91 cm is to be replaced by one cube-shaped box (same overall volume). How long will be its edge? - 3 years

The company has increased the number of employees. In year 1997 compared to 1996 17% more, in 1998 12% more against the previous year, in year 1999 20% more compared to 1998. How many % increase in the number of employees in 3 years?

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