# Examples for 8th grade - page 57

- Reservoir

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

What is the value of ? ? - 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? - Regular triangular prism

Calculate the surface area of body of regular triangular prism, when the length of its base edge is 6.5 cm and height 0.2 m. - CD disc

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

PQRS is a rhombus. Given that PQ=4 cm & height of rhombus is given 1.8 cm. Calculate its area. - 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? - 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 - 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. - 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 ? - 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}? - 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? - Copy typist

Typist for 12 hours rewritten 15% of the manuscript. After how many hours he will done 35% of the manuscript? - Unknown number 5

I think unknown number. If we enlarge it five times then subtract 3 and result decreases by 75% we get the number by one greater than the number I think. What number am I thinking? - 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? - 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. - Fog

The car started in fog at speed 30 km/h. After a 12-minute drive, the fog dissipated and the driver drove next 12 minutes distance 17 km. On the last 17 km long again the driving conditions deteriorated and the driver drove the speed of 51 km/h. a) Calcu - 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? - 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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