# Examples for 8th grade - page 56

- Office

Office building was built in the shape of a regular hexagon inscribed in a circle with a radius of 12 m. The height of the walls is 7m. How much CZK cost plastering the walls of the building, if per 1 m square cost CZK 400? - ABS

What is the value of ? ? - Reservoir

6 m long reservoir has a diameter of 2.2 m. What is its surface area in square meters? - Parallelogram ABCD

The area of parallelogram ABCD is 41 cm^{2.}Points M and N are the midpoints of the sides AB and BC. What is the area of a quadrilateral MBND? - 6-gon

Perimeter of regular hexagon is 41. Calculate its circumradius (radius of circumscribed circle). - Alcohol 2

Two types of alcohol one 70% and second 61% give 11 liters of 57% alcohol. How many liters of each type are in the mixture? - Rhombus

PQRS is a rhombus. Given that PQ=4 cm & height of rhombus is given 1.8 cm. Calculate its area. - Tank 9

The tank with volume V is filled with one pump for three hours and by second pump for 5 hours. When both pumps will run simultaneously calculate: a) how much of the total volume of the tank is filled in one hour b) for how long is the tank full - CD disc

A compact disc has a diameter of 11.8 cm. What is the surface area of the disc in square centimeters? - Copy typist

Typist for 12 hours rewritten 15% of the manuscript. After how many hours he will done 35% of the manuscript? - Cube 9

What was the original edge length of the cube if after cutting 39 small cubes with an edge length 2 dm left 200 dm^{3}? - Colour - billboard

Shelftalker has the shape of a parallelogram. Its length is 4.9 m and the corresponding height is 3.5 meters. Calculate how much (kg) paint must purchase to redecoration if 1 kg cover 4 m^{2}of shelftalker surface. - Seven tractors

Seven tractor plowed 308 ha field in four days. How many hectares of fields will plowe 9 tractors in 3 days at the same power? - Bonbons 2

Kilo sweets will cost 260 CZK. The first type has a price per 320 kg, the second type 240 CZK per kg. How many kilos of both kinds of sweets need to prepare a 77 kg mixture ? - Volume of three cuboids

Calculate the total volume of all cuboids for which the the size of the edges are in a ratio of 1:2:3, and one of the edges has a size 6 cm. - Laths

There are two laths in the garage opposite one another: one 2 meters long and the other 3 meters long. They fall against each other and lean against the opposite walls of the garage both laths and touch at a height of 70 cm above the garage floor. How wide - Holiday SMS

Kucera and Malek start from the holiday together. They agreed that if they be 100 km apart, will send a SMS. Kucera traveling at 60 km/h., Malek 90 km/h. They started at 14 hours PM. At what time they send a message? - Concentration

How 0.5 liters of 8% vinegar diluted to a concentration of 20 hundredths % of vinegar? How many liters of water must be pour? - Three friends

Peter is eight times older than Rado, Rado is 3 times younger than Joseph. Together they have 120 years. Determine how many are each of them. - Dusan

a) Dusan break two same window, which has triangular shape with a length of 0.8 m and corresponding height 9.5 dm. Find how many dm^{2}of glass he needs to buy for glazing of these windows. b) Since the money to fix Dusan has not, must go to the paint job

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