# Examples for 9th grade - page 73

- Average

If the average(arithmetic mean) of three numbers x,y,z is 50. What is the average of there numbers (3x +10), (3y +10), (3z+10) ? - Repair company

The company repairs cars. The first day repair half of the contract second day, the half of the rest and third day 8 residue cars. How many total cars company repaired? - Linear function

What is the equation of linear function passing through points: a) A (0,3), B (3,0) b) A (-2,-6), B (3,4) - Ice cream

Annie likes much ice cream. In the shop are six kinds of ice cream. In how many ways she can buy ice cream to three scoop if each have a different flavor mound and the order of scoops doesn't matter? - Circle's chords

In the circle there are two chord length 30 and 34 cm. The shorter one is from the center twice than longer chord. Determine the radius of the circle. - Water wessel

The vessel containing water has a weight 19 kg. After pouring half the water its weigth 11 kg. What is the weight of the empty vessel? - The ladder

The ladder is 10 m long The ladder is 8 m high How many meters is the distant heel from the wall? - Hockey match

The hockey match ended with result 3:1. How many different storylines may have the match? - Alcohol mixture

From 55% and 80% alcohol we have to produce 0.2 kg of 60% alcohol. How many of them do we use in solution? - Reciprocal equation

Determine the root of the equation: 9/x-7/x=1 - Threesome

Dana, Dalibor and Michael have a combined 57 years. Dana is five years older than Dalibor, but Dana is five years younger than Michael. Determine how old is Dana, Dalibor and Michael. - Savings

Paul has a by half greater savings than half Stanley, but the same savings as Radek. Staney save 120 CZK less than Radek. What savings have 3 boys together? - Fit ball

What is the size of the surface of Gymball (FIT - ball) with a diameter of 65 cm? - Fertilizer

Meadow with an area of 1,500 square meters was fertilized with 12 kg of urea. Urea contains 45% nitrogen. How much nitrogen accounted per 1 m^{2}? - Potatoes 6

The farmer brought potatoes to the market. In the first hour he sold two-fifths of the potatoes brought, in the second hour he sold five-sixth of the remaining potatoes, and in the third hour he had sold the last 40kg of potatoes. How many kg of potatoes d - Cone

The rotating cone volume is 9.42 cm^{3,}with a height 10 cm. What angle is between the side of the cone and its base? - Apples 2

Dried apples contain 15% water. Fresh apples contain 80% water. How many kg of apples we need buy in order to get 3 kg of dried apples? - Internal angles

Find the internal angles of the triangle ABC if the angle at the vertex C is twice the angle at the B and the angle at the vertex B is 4 degrees smaller than the angle at the vertex A. - Hydrostatic force

What hydrostatic force is applied to an area of 30 cm^{2}in water at a depth of 20 m? (Water density is 1000 kg/m3) - Electricity consumption cost

Last year Karol family reduced its electricity consumption by 31% compared to the previous year and paid CZK 2883 less. How many CZK is electricity last year and how many two year ago?

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