# Examples for 8th grade - page 56

- 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. - 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? - 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 100 kg mixture ? - 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? - 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 - The tent

The tent shape of a regular quadrilateral pyramid has a base edge length a = 2 m and a height v = 1.8 m. How many m^{2}of cloth we need to make the tent if we have to add 7% of the seams? How many m^{3}of air will be in the tent? - Areaf of ST

It is given square DBLK with side |BL|=13. Calculate area of triangle DKU if vertex U lie on line LB. - ABS

What is the value of ? ? - 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. - 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 - Sugar cubes

The glass has 600 ml of tea, which represents 80% of the volume of the glass. If you put twenty regular sugar cubes of 2 cm in the tea, how many ml of tea are poured? - 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}? - Internal and external angles

Calculate the remaining internal and external angles of a triangle, if you know the internal angle γ (gamma) = 34 degrees and one external angle is 78 degrees and 40 '. Determine what kind of triangle it is from the size of its angles. - Average speed

What is the average speed you have to move the way around the world in 80 days? (Path along the equator, round to km/h). - Alcohol 2

Two types of alcohol one 70% and second 55% give 13 liters of 63% alcohol. How many liters of each type are in the mixture? - 6-gon

Perimeter of regular hexagon is 113. Calculate its circumradius (radius of circumscribed circle). - 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? - Star

Calculate the content of the shaded part of square with side 19 cm. - Copy typist

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

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