# Examples for 9th grade - page 83

1. 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?
2. Hexagon area The center of the regular hexagon is 21 cm away from its side. Calculate the hexagon side and its area.
3. The gardener The gardener bought trees for 960 CZK. If every tree were cheaper by 12 CZK, he would have gotten four more trees for the same money. How many trees did he buy?
4. Q of GP Calculate quotient of geometric progression if a1=5 a a1+a2=12.
5. Cancer Of the 80 people 50 people ill cancer. What percentage of people isn't ill? The double ladder has 3 meters long shoulders. What is the height of the upper of the ladder reach if the lower ends are 1.8 meters apart?
7. Shots Determine the percentage rate of keeper interventions if from 32 shots doesn't caught four shots.
8. Sum of members What is the sum of the first two members of the aritmetic progression if d = -4.3 and a3 = 7.5?
9. 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
10. Working time At 10 hours work shift, work is done in 16 days. How many days will the work be done at 8 hours shifts? Calculate how many percent will increase the length of an HTML document, if any ASCII character unnecessarily encoded as hexadecimal HTML entity composed of six characters (ampersand, grid #, x, two hex digits and the semicolon). Ie. space as: &#x20;
12. Coefficient Determine the coefficient of this sequence: 7.2; 2.4; 0.8
13. Inscribed circle The circle inscribed in a triangle has a radius 3 cm. Express the area of the triangle using a, b, c.
14. Trapezoidal prism Calculate the surface of the quadrilateral prism ABCDA'B'C'D 'with the trapezoidal base ABCD. The height of the prism is 12 cm; ABCD trapezoidal data: AB base length is 8 cm, CD base length is 3 cm, BC arm length is 4 cm, and AC diagonal length is 7 cm. L
15. MO Z8-I-1 2018 Fero and David meet daily in the elevator. One morning they found that if they multiply their current age, they get 238. If they did the same after four years, this product would be 378. Determine the sum of the current ages of Fero and David.
16. The terrace Around the round pool with a diameter of 5.5 meters is a wooden terrace with a width of 130 cm. What is the area of the terrace?
17. Satin Sanusha buys a piece of satin 2.4 m wide. The diagonal length of the fabric is 4m. What is the length of the piece of satin?
18. Seagull Artificially created island in the shape of a circle with a radius of 50 m is overgrown with grass. The only exception is a landing area for helicopters in the shape of a rectangle measuring 15 m and 8 m. What is the probability that the flying seagull (wi
19. Toy cars Pavel has a collection of toy cars. He wanted to regroup them. But in the division of three, four, six, and eight, he was always one left. Only when he formed groups of seven, he divided everyone. How many toy cars have in the collection?
20. Trapezium The area of trapezium is 35 cm2. Find its altitude if the bases are 6cm and 8 cm.

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