# Examples for 8th grade - page 18

- Pit

Pit has shape of a truncated pyramid with rectangular bases and is 2.8 m deep. The length and width of the pit is the top 3 × 1.5 m bottom 1 m × 0.5 m. To paint one square meter of pit we use 0.3 l of green colour. How many liters of paint is needed when w - Circle in rhombus

In the rhombus is inscribed circle. Contact points of touch divide the sides to parts of length 18 cm and 17 cm. Calculate the circle area. - AVG of INT

What is the average of the integers from 7 throuht 15 inclusive? - Hiker

Hiker went half of trip the first day, the third of trip the second day and remaines 13 km. How long trip he planned? - Cyclist

A cyclist is moving at 26 km/h and follow pedestrian who is walking at speed 7 km/h. Walker has an advantage 13 km. How long take cyclist to catch up with him? - MO - triangles

On the AB and AC sides of the triangle ABC lies successive points E and F, on segment EF lie point D. The EF and BC lines are parallel and is true this ratio FD:DE = AE:EB = 2:1. The area of ABC triangle is 27 hectares and line segments EF, AD, and DB se - Glass mosaic

How many dm^{2}glass is nessesary to produc 50 slides of a regular 6-gon, whose side has length 7 cm? Assume that cutting glass waste is 14%. - Fertilizer

Mr. Gherkin use for fertilization 9% solution of fertilizer. 7 liters of it still left. How much water must be added to the solution to make only 5% solution? - 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} - Map

Forest has an area of 36 ha. How much area is occupied by forest on the map at scale 1:5000? - 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. - Water tank

Water tank shape cuboid has a width of 3.3 m and length twice larger. How high will reach water if water flow into 15 liters of water per second during 23 minutes? - Nine-gon

Calculate the perimeter of a regular nonagon (9-gon) inscribed in a circle with a radius 20 cm. - Lock

Combination lock will open when the right choice of 4 numbers (from 1 to 14 inclusive) is selected. A. How many different lock combinations are possible? B. Is he combination lock named appropriately? - Root

Use law of square roots roots: ? - Reservoir + water

Reservoir completely filled with water weighs 13 kg. After pouring off three quarters of the amount of water weights 4 kg. Calculate the weight and volume of the reservoir. - Event probability

The probability of event G in 9 independent experiments is 0.48. What is the probability that the event G occurs in one experiment (probability is same)? - Intersections

How many intersections have circles with radius 12 dm and 17 dm, if the distance of their centers is 20 dm. - Box

Calculate the angle between box base 5 x 7 and body diagonal length 14. - Shots

2000 lead shots with diameter 2 mm is decanted into a ball. What is it diameter?

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