# Examples for 8th grade - page 102

- Fractions

Three-quarters of an unknown number are 4/5. What is 5/6 of this unknown number? - Mushrooms

Fresh mushrooms contain 88% water, dried 14% water. How many kilograms of fresh mushrooms should be collected to get 3 kg of dried? - Rhombus 29

One of the diagonals of a rhombus is equal to a side of the rhombus. Find the angles of the rhombus. - Sum of squares

The sum of squares above the sides of the rectangular triangle is 900 cm^{2}. Calculate content of square over the triangle's hypotenuse. - Body diagonal

Calculate the cube volume, whose body diagonal size is 75 dm. Draw a picture and highlight the body diagonal. - Regular prism

The regular four-sided prism has a base of 25 cm^{2}and a surface of 210 cm^{2}. Find its volume. - Granules

Katy had two dogs. The first one ate a pack of granules a week and the other two times longer. Katka bought them two bags of granules. How long does it last for both dogs? - Slant height

The slant height of cone is 5cm and the radius of its base is 3cm, find the volume of the cone - Two buses

The first bus runs 15 minutes the second bus runs after 21 minutes. Together they both leave at 7:00 on Monday. When and what day will they meet? - Functions f,g

Find g(1) if g(x) = 3x - x^{2}Find f(5) if f(x) = x + 1/2 - Bulbs

There are 875 identical light bulbs in the sports hall lightning for 2 hours. How long does it lightning 100 this light bulbs? - The factory

The factory z can complete an order in 12 days, factory p in 18 days. For how many days does an order completed when the first two days work only the factory z and then both factories? - Mixture

How many percentages mixtures do we get by adding 23ml of matter to 89ml of water? - Inscribed

Cube is inscribed in the cube. Determine its volume if the edge of the cube is 10 cm long. - Iron ball

The iron ball has a weight of 100 kilograms. Calculate the volume, radius, and surface if the iron's density is h = 7.6g/cm^{3}. - Triplets

Three years ago, the triplets Pavel, Petr, and Luke and their five-year-old sister Jane had together 25 years. How old is Jane today? - Right angled triangle 3

Side b = 1.5, hypotenuse angle A = 70 degrees, Angle B = 20 degrees - Sixty

Sixty percent of one-fifteen of the total is equal to thirty. What are two percent of the total? - Composite ratio

Jakub, Aneta, and Lenka divided 1342 USD in the ratio 5/2: 3/10: 1/4. How much did Lenka take? - A trapezoid

A trapezoid 75 ft wide on top 85 ft on the bottom, the height is 120 ft. What is its area in the square yds?

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