# Expression of a variable from formula - examples - page 14

- Alcohol

How many cubic centimeters of 96% alcohol is needed to obtain 0.75 liter of 40% alcohol? - Sale off

Product cost 95 euros before sale off. After sale off cost 74 euros and 10 cents. About what percentage of produt became cheaper? - Rectangle

The length of the rectangle is 12 cm greater than 3 times its width. What dimensions and area this rectangle has if ts circumference is 104 cm. - VAT on books

The cost of a book in the store is 12.5 euros. How much euros is the VAT of this book? VAT is 10%. - Body diagonal

The cuboid has a volume of 32 cm^{3}. Its side surface area is double as one of the square bases. What is the length of the body diagonal? - Trench

The trench is a four-sided prism. The cross section has a trapezoidal shape with basements of 4m and 6m, the length of the trench is 30m. What is the depth of the trench if we dig 60,000 l of soil. - Workers

9 workers dig a canal 120 meters long for eight hours. For how long would be dig five workers canal 200 meters long? - Contract

8 employees complete the contract for 65 hours. After 17 hours, 3 employees had to leave for another job. How many more hours will the job on contract be fulfilled? - Chocolate roll

The cube of 5 cm chocolate roll weighs 30 g. How many calories will contain the same chocolate roller of a prism shape with a length of 0.5 m whose cross section is an isosceles trapezoid with bases 25 and 13 cm and legs 10 cm. You know that 100 g of this. - Price saleoff

Shoes standing y euros. At first they were discounted by 12% and then 50% of the new amount. After this double cheapening the cost was exactly 22 euros. Determine the original price of shoes. - Variance and average

Of the 40 values were calculated average mx = 7.5 and variance sx = 2.25. After the control was found to lack the two items of the values of x41 = 3.8 and x42=7. Correct the above characteristics (mx and sx). - Unknown number

Determine the unknown number, which double of its fourth square is equal the fifth its square. - Vacation

Tomas spent 60% of his savings for his weekly vacation. He was 32 € left. How many euros did he have before vacation? - Wall diagonal

Calculate the length of wall diagonal of the cube whose surface is 384 cm square. - The cylinder base

The cylinder with a base of 8 dm^{2}has a volume of 120 liters. From a cylinder fully filled with water, 40 liters of water was removed. At what height from the bottom /with precision to dm/ is the water level? - Square s3

Calculate the diagonal of the square, where its area is 0.49 cm square. And also calculate its circumference. - Cows

Agricultural cooperative has increased the number of housed cows by 14% to 285 units. By how many cows increased agricultural cooperative the number of cows? - Quadrangular pyramid

Calculate the surface area and volume of a regular quadrangular pyramid: sides of bases (bottom, top): a1 = 18 cm, a2 = 6cm angle α = 60 ° (Angle α is the angle between the side wall and the plane of the base.) S =? , V =? - Cube walls

Find the volume and surface area of the cube if the area of one wall is 40cm2. - Wine

A bottle of wine costs 21 euros; and wine is 20 times more expensive than a bottle. How much a bottle cost?

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