# Examples for 8th grade - page 17

- Hexagonal pyramid

Calculate the volume and the surface of a regular hexagonal pyramid with a base edge length 3 cm and a height 5 cm. - Cone and the ratio

Rotational cone has a height 23 cm and the ratio of the base surface to lateral surface is 7: 9. Calculate a surface of the base and the lateral surface. - Truck

Truck went for 4 hours and 48 minutes. If truck increase speed by 21 km/h, went same distance in 1.8 hours. Calculate this distance. - Cube wall

Surface of first cube wall his 225 mm^{2}. Second cube area is 60% of the surface of the first cube. Determine the length of the edge of the second cube (x). - Block

Calculate the volume of a cuboid ABCDEFGH if |AB| = 16 cm, |BC| = 19 cm and the angle ∠CDG = 36.9° - Sphere A2V

Surface of the sphere is 296 cm^{2.}What is its volume? - Two balls

Two balls, one 8cm in radius and the other 6cm in radius, are placed in a cylindrical plastic container 10cm in radius. Find the volume of water necessary to cover them. - Scrap

From 6 products are 3 scrap. What is the probability that the random pick of 2 products have no defective product? - Hollow sphere

Steel hollow sphere floats on the water plunged into half its volume. Determine the outer radius of the sphere and wall thickness, if you know that the weight of the sphere is 0.5 kg and density of steel is 7850 kg/m^{3} - Steamship

Between the two ports on the river is going steamship. The journey there and back takes 8:42. Downstream steamship traveling at 20 km/h, upstream 9 km/h. What is the distance between the ports? - Triangle angles

The angles α, β, γ in triangle ABC are in the ratio 6:2:6. Calculate size of angles. - Three workers

Three workers A, B, C have to work on a specific task. Workers A and B completed whole task in 11 days, B together with C for 15 days, A together with C for 24 days. How long it would take to complete the task every one of them alone? How long it would. - Leveling

Calculate how many 25 kg bags of leveling concrete must be purchased if we leveling room 15 m^{2}to the "height" 6 mm if consumtion is 1.5 kg per square meter and millimeter thickness. - Blueberries

Marie earns 3 liters of blueberries for 3.4 hours, Peter 2.4 liters for 2.9 hours. How long have earns together one liter? - Wheat

The rectangle shaped field with dimensions 889 m and 1336 m harvested last year was 6235 q wheat. (1 q = 1 quintal = 100 kg). During the year, it was necessary to fix the pipe and therefore did kick wide 3 m parallel to the side of the field 1336 m, where. - Heron backlaw

Calculate missing side in a triangle with sides 17 and 34 and area 275. - XY triangle

Determine area of triangle given by line 7x+8y-69=0 and coordinate axes x and y. - Christmas Day

In leap years was 53 Sundays. On what day of the week fell to Christmas Day? - Wiring

Conduit has a cross section 48^{2}mm. Maybe put it into 6 conductors with a cross section S2 $mm^{2}? - Coin and die

Flip a coin and then roll a six-sided die. How many possible combinations are there?

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