# Examples for 8th grade - page 36

- Aluminum wire

Aluminum wire of 3 mm diameter has a total weight of 1909 kg and a density of 2700 kg/m^{3}. How long is the wire bundle? - Permill

How many permill is 978 from 84370? - Disinfecting solution

How much distilled water is necessary to pour into 500 ml of 33% hydrogen peroxide solution to obtain 3% disinfecting solution? - Sphere fall

How many percent fall volume of sphere if diameter fall 10×? - Cylinder - h2

Cylinder volume is 2.6 liters. Base area is 1.3 dm^{2}. Calculate the height of the cylinder. - Pedestrian and the cyclist

Pedestrian and cyclist went against each from the two cities that are distant 40 km. Pedestrian started 30 minutes before the cyclist and walk an average speed of 5 km/h. What speed went cyclist when met after 120 minutes from the start of the pedestrian? - Triangular pyramid

Determine the volume and surface area of a regular triangular pyramid having a base edge a=20 cm and a lateral edge b = 35 cm - Square

If we increase one side of square by its one-half then square perimeter increase by 10 cm. What is the side of the square? - 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. - Shadow and light

Nine meters height poplar tree has a shadow 16.2 meters long. How long shadow have at the same time Joe if he is 1,4m tall? - Conserving water

Calculate how many euros are spent annually on unnecessary domestic hot water, which cools during the night in pipeline. Residential house has 129 m of hot water pipelines 5/8" and the hot water has a price of 7 Eur/m^{3}. - Scale

Cylinder was drawn in scale 2:1. How many times is the volume of the cylinder smaller in reality? - Brothers and sisters

Lenka has as many brothers as sisters. Her brothers have twice as many sisters as brothers. How many brothers and sisters are in the family? - Peleton

Cycling race was run at an average speed of 45 km/h. One cyclist lost with defect 8 minutes. How long and how far he must go at speed 51 km/h to catch peleton again? - Sports games

Pupils of same school participated district sports games. When dividing into teams found that in the case of the creation teams with 4 pupils remaining 1 pupil, in the case of a five-member teams remaining 2 pupils and in the case of six-members teams r - Tin with oil

Tin with oil has the shape of a rotating cylinder whose height is equal to the diameter of its base. Canned surface is 1884 cm^{2}. Calculate how many liters of oil is in the tin. - 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 - Clock hands

The hands on the clock shows the time 12 hours and 2 minutes. Calculate the size of a sharp angle between clock hands three hours later. - Drunk and alcohol

One drunk measured 2.7 ‰ alcohol in the blood, another 1.75 ‰. How many grams of alcohol in the blood they had if they has 6 kg of blood? - Louvers

The company charges for office equipment louvers total 262 Eur. From the delivery bill is obvious that the louvers are 76 Eur expensive than their installation. What percentage of the total charged is the installation of louvers?

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