# Examples for 9th grade - page 98

1. Ladder Adam placed the ladder of the house, the upper end reaching to the window at the height of 3.6m, and the lower end standing on level ground and was distant from a wall of 1.5m. What is the length of the ladder?
2. Resistance A resistor having an electrical resistance of 1.5 k ohms passes an electrical current of 0.1 A. Calculate what voltage is between the terminals of the resistor.
3. Pavement Calculate the length of the pavement that runs through a circular square with a diameter of 40 m if distance the pavement from the center is 15 m.
4. Practice How many ways can you place 20 pupils in a row when starting on practice?
5. Inverted nine In the hotel,, Inverted nine" each hotel room number is divisible by 6. How many rooms we can count with three-digit number registered by digits 1,8,7,4,9?
6. Associative law multiplication In a warehouse, you obtain a 20% discount but you must pay a 15% sales tax. Which would you prefer to have calculated first: discount or tax? Explain. (result write as: 1 = first discount, 2 = first tax, 3 = no matter what first)
7. Cancel fractions Compress the expression of factorial: (n+6)!/(n+4)!-n!/(n-2)!
8. An angle An angle x is opposite side AB which is 10, and side AC is 15 which is hypotenuse side in triangle ABC. Calculate angle x.
9. Driver The driver of the car at a speed of 100 km/h faced the obstacle and began to brake with a slowing of 5 m/s². What is the path to stopping the car when the driver has registered the obstacle with a delay of 0.7 s?
10. Spherical cap Place a part of the sphere on a 4.6 cm cylinder so that the surface of this section is 20 cm2. Determine the radius r of the sphere from which the spherical cap was cut.
11. On a farm On a farm, there are 90 rabbits, 700 sheep, 300 cattle and 500 pigs. What percentage of the total number of animals are rabbits?
12. Cube cut The cube ABCDA'B'C'D ' has an edge of 12cm. Calculate the area of diagonal cut B DD'B '.
13. A candle A candle shop sells scented candles for \$16 each and unscented candles for \$10 each. The shop sells 28 candles today and makes \$400. a. Write a system of linear equations that represents the situation. b. Solve the system to answer the questions: How m
14. Carrot seed Carrot seed germination is 85%, weight 1000 carrots seeds are 2.4g. How many seeds are likely to germinate if we sow 8g of seeds?
15. Digits Show that if x, y, z are 3 consecutive nonzero digits, zyx-xyz = 198, where zyx and xyz are three-digit numbers created from x, y, z.
16. Three points Three points A (-3;-5) B (9;-10) and C (2;k) . AB=AC What is value of k?
17. 2 pipes 2 pipes can fill a tank in 35 minutes. The larger pipe alone can fill the tank in 24 minutes less time than the smaller pipe. How long does each pipie take to fill the tank alone?
18. Average height The average height of all pupils is 162 cm. The class teacher's height is 178 cm. The average height of all (teacher and all pupils) is 163 cm. Calculate the number of pupils in the class.
19. Commission Daniel works at a nearby electronics store. He makes a commission of 15%, percent on everything he sells. If he sells a laptop for 293.00\$ how much money does Daniel make in commission?
20. Sheep and cows There are only sheep and cows on the farm. Sheep is eight more than cows. The number of cows is half the number of sheep. How many animals live on the farm?

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