# Examples for 8th grade - page 57

- Strange x

For what x is true ?? - 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? - Price reduction

Price of camera is 654 USD on sale its price reduced to 411 USD. Calculate the percentage reduction in the price of the camera. - Candelas

We burned two unequally thick and long candles. Longer burnt for three and a half hours and shorter for five hours. After two hours of burning it was identical. How many times was longer candle longer then shorter? - Children

Less than 20 children is played various games on the yard. They can create a pairs, triso and quartets. How many children were in the yard when Annie came to them? - Dog

Dog is tied to a chain, which is mounted in a corner of the yard. Yard has the shape of a square with a side length of 20 meters. The same long is also dogchain. Are there places in the yard where dog can't reach? - 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. - 5 pumps

Five pump to pump 3 hours 1600 hl of water. How long pumped same amount of water 4 pumps? - Isosceles triangle

Calculate area and perimeter of an isosceles triangle ABC with base AB if a = 6 cm, c = 7 cm. - Reservoir

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

PQRS is a rhombus. Given that PQ=3 cm & height of rhombus is given 2 cm. Calculate its area. - 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. - Mr. Vojta

Mr. Vojta put in the bank 35000 Kč.After a year bank him credited with interest rate of 2% of the deposit amount. How then will Mr. Vojta in the bank? - 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 - Alcohol 2

Two types of alcohol one 63% and second 75% give 20 liters of 69% alcohol. How many liters of each type are in the mixture? - 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). - 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? - 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 - Grid/network of cube

Grid of cube has a circumference 42 mm. Calculate the surface area of the cube ... - 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.

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