# Examples for 8th grade - page 87

- Regular n-gon

Which regular polygon have a radius of circumscribed circle r = 10 cm and the radius of inscribed circle p = 9.962 cm? - Map scale

On a 1:1000 scale map is a rectangular land of 4.2 cm and 5.8 cm. What is the area of this land in square meters? - Content area and percents

Determine what percentage is smaller cube surface, when the surface area of the wall decreases by 25%. - Linear system

Solve this linear system (two linear equations with two unknowns): x+y =36 19x+22y=720 - Volleyball

8 girls wants to play volleyball against boys. On the field at one time can be six players per team. How many initial teams of this girls may trainer to choose? - Tree trunk

From the tree trunk, the diameter at the narrower end is 28 cm, a beam of square cross-section is to be made. Calculate the longest side of the largest possible square cross-section. - Two sisters

Two sisters together have 54 CDs. 6/8 CDs has younger sister and is equal to 3/5 of CDs older sisters. How many CDs has each of the sisters? - Cube walls

Find the volume and surface area of the cube if the area of one wall is 40cm2. - Boxes

200 boxes have been straightened in three rows. The first was 13 more than in the second, and in the second was one fifth more than in the third one. How many boxes are in each row? - Acid solution

By adding 250 grams of a 96% solution of sulfuric acid to its 3% solution its initial concentration was changed to 25%. How many grams of 3% of the acid were used for dilution? - Triangular prism

The perpendicular triangular prism is a right triangle with a 5 cm leg. The content of the largest wall of the prism is 130 cm^{2}and the body height is 10 cm. Calculate the body volume. - Syringe and patient

In 1 ampoule of 2 ml is 15 mg of Dipidol. The patient should receive 10 mg. How much ml do I draw into the syringe? - Football season

Dalibor and Adam together scored 97 goals in the season. Adam scored 9 goals more than Dalibor. How many goals scored each? - Rhombus OWES

OWES is a rhombus given that OW 6cm and one diagonal measures 8cm. Find its area? - Washing mashine

Family buy a washing machine for 350e. Cash paid 280e. What percentage of the total price must still pay the washer? - Kaufland sales-off

As a rule the goods to the approaching end consumption in Kaufland three days before the end of the consumption to 30% off and one day before the end of the consumption to 50% discounts. Sometimes however the seller has been mistaken and the second discoun - Tank diameter

A cylindrical tank has a volume of 60 hectoliters and is 2.5 meters deep. Calculate the tank diameter. - Water temperatures

To 25 liters of water at 50 °C we add 15 liters of water at a different temperature. How many °C should the water be colder than 50 °C so that 40 liters of the water obtained has a temperature 42.5 °C? - Hypotenuse

Calculate the length of the hypotenuse of a right triangle if the length of one leg is 4 cm and its content area is 16 square centimeters. - Triangle ABC

Construct a triangle ABC is is given c = 60mm hc = 40 mm and b = 48 mm analysis procedure steps construction

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