# Examples for 8th grade - page 43

- Rectangular trapezoid

Calculate the content of a rectangular trapezoid with a right angle at the point A and if |AC| = 4 cm, |BC| = 3 cm and the diagonal AC is perpendicular to the side BC. - Round table tablecloth

Round table has area 50.24 dm^{2.}Calculate the diameter of the circular tablecloth, if it is extend beyond the edge of the table by 30 cm. - Two workers

Two workers make 138 parts/items. The first one produces 30% more than the second. How many items will each produce? - Parcel

Both dimensions of the rectangular parcel were increased by 40%. By how many % has increased its acreage? - 6 regular polygon

It is given 6 side regular polygon whose side is 5 cm. Calculate its content area. Compare how many more cm^{2}(square centimeters) has a circle in which is inscribed the 6-gon. - Barrel 2

Empty barrel weighs 12 kg. When it filled with water up to 46% height, weighs 68 kg. How heavy is barrel full of water? - Machines 2

2 machines for 50 hours produces 2,000 products. How many machines need to buy to make in 30 hours 15,000 products? - Wheel

How many times turns the wheel of a passenger car in one second if car run at speed 89 km/h. Wheel diameter is d = 62 cm. - Total displacement

Calculate total displacement of the 12-cylinder engine with the diameter of the piston bore B = 6.8 cm and stroke S=2 cm of the piston. Help: the crankshaft makes one revolution while the piston moves from the top of the cylinder to the bottom and back t - Water reservoir

The water reservoir is filled with one pump for 4 days by the second one for 9 days. Outlet can drain tank in 12 days. How long take fill the reservoir if both pumps are running and not closed outlet channel. - Prism

The volume of tetrahedral prism is 2.43 m^{3.}Base of prism is a parallelogram in which a side 2,5dm and height ha = 18cm. Calculate the height of the prism. - Circular flowerbed

Circular flowerbed with diameter 8 m we split by concentric circle to circle and annulus with the same area. Determine the radius of the circle. - Nuts, girl and boys

Milena collected fallen nuts and called a bunch of boys let them share. She took a condition: the first boy takes one nut and tenth of the rest, the second takes 2 nuts and tenth new rest, the third takes 3 nuts and tenth new rest and so on. Thus managed. - Wood

Wood contains 12% water. 1 m^{3}of wood weighs 650 kg. How many liters of water it contains? - Water level

The glass container has a cuboid shape with dimensions of the bottom 24 cm and 12 cm. The height of water is 36 cm. Calculate the volume of the body, which are sunk into the water if the water level rise by 3 cm. - Olympics

In how many ways can be placed 6 athletes on the podium at the Olympics? Depend on the color of the metal. - Dig water well

Mr. Zeman digging a well. Its diameter is 120 cm, and plans to 3.5 meters deep. How long (at least) must be a ladder, after which Mr. Zeman would have eventually come out? - Map scale

Garden has on plan on a scale of 1: 150 width 22 cm and length 35 cm. What is the real area of the garden? - Cuboid - simple

Calculate the surface area and volume of a cuboid if a = 8 cm, b = 14 cm and c = 6 cm. - Midpoint of segment

Point A has coordinates [15; 1] and the midpoint of the segment AB is the point [-20; 13]. What are the coordinates of point B?

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