# Examples for 9th grade - page 81

- Three cubes

The body was created by gluing three identical cubes. Its volume is 192 cm^{3.}What is its surface in dm^{2}? - Red balls

In the bag there are 3 red, 12 blue and 8 green balls. How many red balls we must be attached to the bag if we want the probability of pulling out the red balls was 20%? - Three friends

Danica, Lenka and Dalibor have altogether 96 kg. Lenka weighs 75% more than Dalibor and Danica weighs 6 kg more than Dalibor. Determine the weight of Danice, Lenka and Dalibor. - Quotient

Determine the quotient and the second member of the geometric progression where a3=10, a1+a2=-1,6 a1-a2=2,4. - Diagonals

Given a rhombus ABCD with a diagonalsl length of 8 cm and 12 cm. Calculate the side length and content of the rhombus. - Coach

Average age of 24 players and a coach of one team is 24 years. The average age of players without a coach is 23 years. How old is the coach? - Trees

Along the road were planted 250 trees of two types. Cherry for 60 CZK apiece and apple 50 CZK apiece. The entire plantation cost 12,800 CZK. How many was cherries and apples? - Three granaries

Three granaries hold 7,800 metric cent (q) of grain. In the first, 70 tonnes of grain was more than the second and in the third it was 120 tonnes less than in the second. How many grain were in each granary? - Two lands

The common area of the two neighboring lands is 964 m^{2.}The second land is 77 m^{2}smaller than twice the size of the first land. Find the areas of each land. - Cross section

The cross-section ABCD of a swimming pool is a trapezium. Its width AB=14 meters, depth at the shallow end is 1.5 meters and at the deep end is 8 meter. Find the area of the cross-section. - Years

Susan is 3 years and as she will be old as Teodor now him will be 11. How old is Teodor today? - Forces on earth directions

A force of 60 N [North] and 80 N [East] is exerted on an object wigth 10 kg. What is the acceleration of the object? - Conical area

A right angled triangle has sides a=12 and b=19 in right angle. The hypotenuse is c. If the triangle rotates on the c side as axis, find the volume and surface area of conical area created by this rotation. - Hexagon area

The center of the regular hexagon is 21 cm away from its side. Calculate the hexagon side and its area. - Q of GP

Calculate quotient of geometric progression if a1=5 a a1+a2=12. - Trapezium ABCD

In the figure, ABDC is a trapezium in which AB || CD. line segments RN and LM are drawn parallel to AB such that AJ=JK=KP. If AB=0.5m and AP=BQ=1.8m, find the lengths of AC, BD, RN and LM. angle D=angle C=60 - Cancer

Of the 80 people 50 people ill cancer. What percentage of people isn't ill? - Sum of members

What is the sum of the first two members of the aritmetic progression if d = -4.3 and a3 = 7.5? - Shots

Determine the percentage rate of keeper interventions if from 32 shots doesn't caught four shots. - Coefficient

Determine the coefficient of this sequence: 7.2; 2.4; 0.8

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