# Examples for 8th grade - page 9

- Sea water

Seawater contains about 7% salt. How many dm^{3}of distilled water we must pour into 14 dm^{3}of sea water to get water with 1.7% salt? - Cube - angles

Calculate angle between the wall diagonal and cube base. Calculate the angle between the cube body diagonal and cube base. - Negative percentage

In 2003, the company had a loss of 25600 Euros. Two years later he was already in profit 25200 Eur. Calculate what percentage of the company increased profits in this two years. - MO SK/CZ Z9–I–3

John had the ball that rolled into the pool and it swam in the water. Its highest point was 2 cm above the surface. Diameter of circle that marked the water level on the surface of the ball was 8 cm. Determine the diameter of John ball. - Kites

Boys run kite on a cable of 86 meters long. What is the kite altitude, if the angle from the horizontal plane is 77°? - Workers

Workers A and B will done work together for 20 days. They worked together 18 days. Then A worker became ill and worker B finish the job alone for 11 days. If every worker was working alone, how many days took whole work for worker A and B? - Camel

Camel owner wants to get out of the city into oasis. He bought 3000 bananas, which wants to sell in oasis. However oasis from the city divided 1,000 kilometers of desert. Camel can carry at one time up to 1000 bananas, and for every kilometer traveled, ea - Ladder

Ladder 5 m long is leaning against the wall. It foot is 0.9 m away from the wall. In which height ladder touch the wall? - Workers

Two workers fulfill a certain task when working together for 7 days, the first if he worked himself done work in 18 days. How many days will do whole job a second worker? - Arc and segment

Calculate the length of circular arc l, area of the circular arc S_{1}and area of circular segment S_{2}. Radius of the circle is 49 and corresponding angle is ?. - Rotation of the Earth

Calculate the circumferential speed of the Earth's surface at a latitude of 53.7°. Consider a globe with a radius of 6378 km. - Plastic pipe

Calculate weight of the plastic pipe with diameter d = 60 mm and length 400 cm if the wall thickness is 6 mm and the density of plastic is 1228 kg/m^{3.} - Tape

Video is 250% more expensive than tape recorder. How many percent is tape recorder less expensive than video? - Gear wheels

Two gear wheels, which fit together have number of teeth z_{1}=132 and z_{2}=123. Calculate the speed of the first wheel, if the second wheel rotates 247 revolutions per minute. - 2nd class variations

From how many elements you can create 6480 variations of the second class? - Rhombus

Find the length of the other diagonal and area of rhombus. The perimeter of a rhombus is 40 cm and one of the diagonals is of length 10 cm. - Pump

What power has a pump output to move 4502 hl of water to a height of 32 m for 5 hours? - Cylinder - basics

Cylinder with base radius r = 37 cm and height h=74 cm. Calculate: - Number ratio

Calculate two positive numbers that its ratio is 4:4 and sum was 184. - Climb

On the road sign, which informs the climb is 20%. Car goes 5 km along this road. What is the height difference that car went?

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