# Examples for 8th grade - page 7

- Maximum area of rhombus

Calculate the interior angles at which equilateral rhombus has maximum area. - Barrel of oil

Barrel of oil weighs 253 kg. When it mold 43% oil, weighed 159 kg. What is the mass of the empty barrel? - Cone

Circular cone of height 15 cm and volume 10598 cm^{3}is at third of the height (measured from the bottom) cut plane parallel to base. Calculate the radius and circumference of the circular cut. - Rectangle

In rectangle ABCD with sides |AB|=19, |AD|=16 is from point A guided perpendicular to the diagonal BD, which intersects at point P. Determine the ratio ?. - Pediatrician

Pediatrician this month of 21 working days takes 3 days holidays. What is the probability that on Monday will be at work? - Rhombus and inscribed

Rhombus has side a = 42 cm, the radius of the inscribed circle is r = 18 cm. Calculate the length of its two diagonals. - Expansion

If one side of the rectangle is larger 4-times and second 2-times, what percentage increases the area of rectangle? - Radians

Convert 270° to radians. Write result as multiple of number π. - Cube zoom

How many percent we increase volume and surface of cube, if we magnify its edge by 38%. - Tangents

To circle with a radius of 41 cm from the point R guided two tangents. The distance of both points of contact is 16 cm. Calculate the distance from point R and circle centre. - Rectangle - sides ratio

Calculate area of rectangle whose sides are in ratio 3:13 and perimeter is 673. - Cu thief

The thief stole 122 meters copper wire with cross-section area of 95 mm^{2.}Calculate how much money gets in the scrap redemption, if redeemed copper for 5.5 eur/kg? The density of copper is 8.96 t/m^{3}. - Daily average

Calculate the average temperature during the day, when 13 hours was 22 °C and 11 hours was 17 °C. - Arc

Circle arc corresponding to angle is 32° is 28 dm long. What is the length of the entire circle? - Lathe

From the cube of edge 37 cm was lathed maximum cylinder. What percentage of the cube is left as waste after lathed? - Sea water

Mixing 94 kg of sea water with 82 kg rainwater is created water containing 4.2% salt. How many percent sea water contains salt? - Pedestrian up-down hill

Pedestrian goes for a walk first at plane at 4 km/h, then uphill 3 km/h. Then it is in the middle of the route, turns back and goes downhill at speed 6 km/h. Total walk was 6 hours. How many kilometers went pedestrian? - Medians

Calculate the sides of a right triangle if the length of the medians to the legs are t_{a}= 21 cm and t_{b}=12 cm. - Kites

Boys run kite on a cable of 68 meters long. What is the kite altitude, if the angle from the horizontal plane is 72°? - Described

Calculate perimeter of the circle described by a triangle with sides 478, 255, 352.

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