# Examples for 9th grade - page 19

- Reservoir + water

Reservoir completely filled with water weighs 13 kg. After pouring off three quarters of the amount of water weights 4 kg. Calculate the weight and volume of the reservoir. - Height

Calculate height of the equilateral triangle if its perimeter is 54? - Electronics: Resistors in parallel

From relation for calculating the resistance of parallel combination of resistors: ? Calculate the R, if R_{1}= 8kΩ a R_{2}= 18kΩ - Sector

The perimeter of a circular sector with an angle 2 rad is 53 cm. Determine the radius of the circle from which the sector comes. - Horizon

The top of a lighthouse is 12 m above the sea. How far away is an object which is just “on the horizon”? [Assume the earth is a sphere of radius 6378.1 km.] - Circles

Area of circle inscribed in a square is 6. What is the area of a circle circumscribed around a square? - Lines

In how many points will intersect 11 different lines, where no two are parallel? - Axial section

Axial section of the cylinder has a diagonal 18 cm. The size of the shell and the base surface are in the ratio 2:3. Calculate the volume and surface area of this cylinder. - Cathethus and the inscribed circle

In a right triangle is given one cathethus long 14 cm and the radius of the inscribed circle of 5 cm. Calculate the area of this right triangle. - Glass of juice

Glass of juice shaped cylinder 16 cm height and base diameter of 10 cm is filled with juice so that the level is 3 cm below the rim of the glass. Determine the maximum angle of the cup can be tilted and juice don't overflow. - Subsets

How many is subsets of set ?? - Salary

Clerk got to pay 1200 Euros in banknotes of 50 and 200 Eur. Total got 9 banknotes. How many was which? - Pizza

A school survey found that 9 out of 16 students like pizza. If 5 students are chosen at random, what is the probability that all 5 students like pizza? - Height difference

What height difference overcome if we pass road 1 km long with a pitch21 per mille? - Distance

Calculate distance between two points Z[7; -9] and U[-10; -8]. - Icerink

Rectangular rink with dimensions of 79.5 m and 529 dm must be covered with a layer of ice 4.5 cm thick. How many liters of water is necessary for the formation of ice when the volume of ice is 10.9% greater than the volume of water. - Cuboid

Cuboid ABCDEFGH with 10 cm height has a base edge length 6 cm and 8 cm. Determine angle between body diagonal and the base plane (round to degrees). - Trains for people

It is said that the train is synonymous to delay. Calculate the average speed of travel by train long 50 km, with regular train leave at 6:05 and arrive at 7:20, but train is late and has departure at 9:52 and arrive at 11:05. - Tank

In the middle of a cylindrical tank with a bottom diameter 350 cm is standing rod which is 31 cm above the water surface. If we bank rod its end reach surface of the water just by the tank wall. How deep is the tank? - Triangle KLB

It is given equilateral triangle ABC. From point L which is the midpoint of the side BC of the triangle it is drwn perpendicular to the side AB. Intersection of perpendicular and the side AB is point K. How many % of the area of the triangle ABC is area o

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