# Examples for 8th grade

- Workers 2

Worker dug the trench for 7 hours, another worker for 10 hours. They recruited to work even one worker more. Digging should be done for 2 hours. For how long would dig third worker alone? - Cube - wall

V kocke ABCDEFGH je ?. Aký je povrch kocky? - Weights

Marry and John together weighing 49 kg. Their weights are in ratio 1:6. Determine their weights. - Two trains

Two trains go at each other. First at speed 40 km/h and the second at speed 60 km/h. At what distance will be 30 minutes before they will meet? - Chord 5

It is given circle k / S; 5 cm /. Its chord MN is 3 cm away from the center of the circle . Calculate its length. - Two looms

On two different looms with different performance can be make required quantity of textile in 6 hours when both work together. On the first machine this quantity of the textile can make in 10 hours. How long should take make same quantity of textile on a - Barrel 4

Barrel of water weighs 63 kg. After off 75% water, the weight of the barrel with water is 21 kg. How many kg weigh empty barrel and how many kgs water in it? - Savings and retirement

The older sibling has saved 44% more euros than the youngest, which represents 22 euros. How many euros older brother has saved ? - Two tributaries

Two tributaries of the pool fill it in 10 hours. One of the tributaries would fill 15 hours. How long would fill the first tributary? - Rectangle - sides 4

Perimeter of the rectangle is 72 cm. Calculate the length of the sides that are in the ratio 3:5. - Semicircle

To a semicircle with diameter 10 cm inscribe square. What is the length of square sides? - Diagonal in rectangle

In that rectangle ABCD is the center of BC point E and point F is center of CD. Prove that the lines AE and AF divide diagonal BD into three equal parts. - Cubes

Most how many cubes with an edge length of 5 cm may fit in the cube with the inner edge of 0.4 m? - Truck PRG-BA

Truck driving on highway from Prague to Bratislava at average speed of 72 km/h. At the moment when the truck passes 54 kilometer from Prague passenger car departs from Prague which travel to Bratislava at speed 90 km/h. When and where (at waht highway k - Bronze, tin and copper

Bronze is an alloy of tin and copper. An alloy of 10% tin and 90% copper is Gunmetal. If it contains 20% tin and 80% copper, it is bell metal. How many tons of molten bell metal and how many tons of copper is needed to make 100 tons of Gunmetal? - Points on circle

In the Cartesian coordinate system with the origin O is a sketched circle k /O; r=2 cm/. Write all the points that lie on a circle k and whose coordinates are integers. Write all the points that lie on the circle I / O; r=5 cm / and whose coordinates are - Tree trunk

From the tree trunk, the diameter at the narrower end is 28 cm, a beam of square cross-section is to be made. Calculate the longest side of the largest possible square cross-section. - Savings 2

Jozef and Michael saved 46 euros together. Michael saved 22 euros more than Jozef. How much did save each of them? - Brigade

On a weekly forest brigade operates 12 students. After plant one hundred spruces get x CZK, anfter one hundred pines y CZK. How many CZK got one student for one day if planted spruces 25000 and 30000 pines week? - Diamond perimeter

Calculate the diamond circumference which area is 288 cm square and one diagonal has a size of 124 cm.

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