# Examples for 8th grade - page 58

- Ethnicity

Share of ethnicity XY is 10%, which is 1/9 more than in the prewar period. What was the share of that ethnicity in the pre-war period? - Square circles

Calculate the length of the described and inscribed circle to the square ABCD with a side of 5cm. - Wheel diameter

A 1m diameter wheel rolled along a 100m long track. How many times did it turn? - Percent chaining

Calculate 20% from 70% from 80 km - Work at plant

Handyman has vowed to do repair work at the plant for 25 days. However, work had to be shortened and therefore gained helper. Together they made all the corrections for 13 1/3 days. How long the work would take helper himself? - School year

At the end of the school year has awarded 20% of the 250 children who attend school. Awat got 18% boys and 23% of girls. Determine how many boys and how many girls attend school. - The chord

Calculate a chord length which the distance from the center of the circle (S, 20 cm) equals 7 cm. - Pyramid in cube

In a cube with edge 12 dm long we have inscribed pyramid with the apex at the center of the upper wall of the cube. Calculate the volume and surface area of the pyramid. - Football league

In the football league is 16 teams. How many different sequence of results may occur at the end of the competition? - Coal

If the daily consumption of 1.6 tons of coal, it is sufficient to supply the boiler for 42 days. How long is sufficient to supply when will burn only 1.2 tons of coal a day ? - Typing course

Before taking a typing course, Seth could type 30 words per minute. By the end of the course, he was able to type 66 words per minute. Find the percent increase. - Hexa prism

Determine the volume of hex prism with edge base 4 cm. The body height is 28 cm. - Painters

15 painters painted fence for 280 minutes. For how many minutes paint half of this fence 12 painters? - Uranium ore

Uranium ore contains 0.2% of pure uranium and pure uranium contains 0.07% of fissile uranium. How many grams of fissile uranium contains 2200 ton of uranium ore? - 4 pipes

The tank flows out by 4 pipes in 6 hours 120 hl water. How much water flows out of 5 pipes of the same diameter in 14 hours? - The book

If one day you read p pages, you will read the book 24 days. If you read each day 10 pages more, you would read a book in 16 days. How many pages have the book? - Grid/network of cube

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

The largest angle at which the lift rises is 16°31'. Give climb angle in permille. - Pupils at cinema

Alena bought movie tickets for two groups of pupils. The first group purchased 7 tickets for 1st and 5 tickets for 2nd place and she pay 62Kč. For the second group bought 11 tickets for 1st and 4 tickets for 2nd place and pay 82Kč. How much was the ticket - Similarity

ABC is a triangle wherein a = 4 cm, b = 6 cm, c = 8 cm. Is it similar to the triangle DEF: d = 3 cm, e = 4.5 cm, f = 6 cm? If so, determine the ratio of similarity.

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