# Examples for 9th grade - page 17

- Hollow sphere

Steel hollow sphere floats on the water plunged into half its volume. Determine the outer radius of the sphere and wall thickness, if you know that the weight of the sphere is 0.5 kg and density of steel is 7850 kg/m^{3} - Two balls

Two balls, one 8cm in radius and the other 6cm in radius, are placed in a cylindrical plastic container 10cm in radius. Find the volume of water necessary to cover them. - Water tank

Water tank shape cuboid has a width of 3.3 m and length twice larger. How high will reach water if water flow into 15 liters of water per second during 23 minutes? - Nine-gon

Calculate the perimeter of a regular nonagon (9-gon) inscribed in a circle with a radius 20 cm. - Lock

Combination lock will open when the right choice of 4 numbers (from 1 to 14 inclusive) is selected. A. How many different lock combinations are possible? B. Is he combination lock named appropriately? - Cinema

Cinema auditorium is built for 3591 people. The first row is planned for 39 seats and each next gradually 3 more. How many rows of seats will have auditorium? - Root

Use law of square roots roots: ? - 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. - Event probability

The probability of event G in 9 independent experiments is 0.48. What is the probability that the event G occurs in one experiment (probability is same)? - Triangular prism

The base perpendicular triangular prism is a right triangle whose hypotenuse measures 13 cm and one cathetus 2 cm. Height of the prism is equal to 10/7 of the perimeter of the base. Calculate the surface area of prism. - Lord Ram

When lord Ram founded the breed white sheep was 8 more than black. Currently white sheep are four times higher than at the beginning and black three times more than at the beginning. White sheep is now 42 more than the black. How many white and black sh - Dices

We will throw two dice. What is the probability that the ratio between numbers on first and second dice will be 1:2? - Balance

The rod are 1.7 m long hanging weights 2 kg and 12 kg on ends. Where are centre of rod (distance from weight 2 kg) to be in balance? - Shooter

The probability that a good shooter hits the center of the target circle I is 0.22. The probability that the target hit intercircle is II 0.41. What is the probability that it hits the target circle I or II? - Inscribed rectangle

The circle area is 184. Determine the area of inscribed rectangle with one side 10 long. - Circumscribing

Determine the radius of the circumscribed circle to the right triangle with legs 3 cm and 3 cm. - Sales vs profit

Apple sells 45 percent less computes than the Acer but the profit from their sales is 1.7 times higher than Acer. How many times are Apple computer more expensive than Acer? - Felix

Calculate how much land saw Felix Baumgartner after jump from 22 km above ground. The radius of the Earth is R = 6378 km. - Isosceles III

The base of the isosceles triangle is 24 cm area 416 cm^{2.}Calculate the perimeter of this triangle. - Machine

Price of the new machine is € 56000. Every year is depreciated 16% of residual value. What will be the value of the machine after 5 years?

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