# Examples for 8th grade - page 48

- Concentration

How 0.5 liters of 8% vinegar diluted to a concentration of 20 hundredths % of vinegar? How many liters of water must be pour? - Water pool

Pool with volume 990hl completely filled, if water flows by one tap 8 hours and by second tap 6 hours. First tap give 10hl more than second per hour. How many hl flows in each of them in an hour? - Reservoir

6 m long reservoir has a diameter of 2.2 m. What is its surface area in square meters? - Chord AB

What is the length of the chord AB if its distance from the center S of the circle k(S, 71 cm) is 27 cm? - Circle sector

Circular sector with a central angle 10 ° has area 254 cm^{2.}Calculate its radius r. - Building base

Excavation for the building base is 350x600x26000. Calculate its volume in m^{3.} - For thinkings

The glass cube dive into the aquarium, which has a length of 25 cm, width 20 cm and height of 30 cm. Aquarium water rises by 2 cm. a) What is the volume of a cube? b) How many centimeters measure its edge? - The cylindrical container

The container has a cylindrical shape the base diameter 0.8 meters has a content area of the base is equal to the content area of the shell. How many full liters of water can be poured maximally into the container? - Car rent

Rental cars are paid a fixed daily fee plus 16 cents for each kilometer traveled. Samuel want to rent a car for a day and worked out that will pay 175 euros. When paying he got a 20% discount on the daily fee, the cost per kilometer is unchanged. Samuel th - Rhombus 2

Calculate the area of rhombus which has a height v=48 mm and shorter diagonal u = 60 mm long. - Sales stores

The first sales store passed the 1/3 and the second 2/5 of the total amount of goods.In third store passed the 2/3 rest of the goods. The remaining 40 kg of goods put into fourth store. How many kilograms of goods pass to a third store? - Unknown number 10

Number first increased by 30%, then by 1/5. What percentage we've increased the original number? - Square and circle

Into square is inscribed circle with diameter 10 cm.What is difference between circumference square and circle? - Again saw

From the trunk of the tree we have to a sculpture beam with rectangular cross-section with dimensions 128 mm and 140 mm. What is the trunk smallest diameter? - Square roots

What is equal to the product of the square roots of 540225? - Cars

Cars started at 7:00 AM. From point A car run at 40 km per hour, from B car run 70 km per hour. Between A and B is 250 km long road. When and where will meet (measured from point A)? - Rectangle - sides 3

If in the rectangle ABCD we enlarge the side a by 5 cm and decrease the side b by 2 cm, the rectangle area will be reduced by 5 cm². When we decrease the length of the side a by 4 cm and and at the same time we increase the length of side b by 3 cm we incr - Two cars

Car A1 goes at average speed of 133 km/h and the second car A2 goes at 128 km/h. How many second will it take car A1 to circulate car A2? Assume that both cars are 4.7 meters long and the safety gap between cars is 2.7 meters. - Flowerbed 2

Around the square flower bed in a park is sidewalk 1.4 m wide. The area of this sidewalk is 125 m^{2.}What is the area of the flowerbed? - Tram

In the three-part tram went 109 passengers in front of others, 92 after others and in the middle half of all. How many passengers went in tram total?

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