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# Ratio & proportion

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### Ratio & proportion

1. 1. RATIO &PROPORTIONSMPK PENABUR GS
2. 2. DO NOW (not later):• Compare the number of boys to girls in the class.
3. 3. • The number of boys =• The number of girls =• If we compare boys to girls we get ___ boys to _____ girls.
4. 4. What do we call a comparisonbetween two or more quantities? We just found the RATIO RATIO of boys to girls. Is the ratio of girls to boys the same ? No, when writing a ratio, ORDER matters.
5. 5. AIM:What is a ratio?
6. 6. DEFINITION OF RATIOA ratio is the comparisonof two or more numbers(quantities).A ratio has no units
7. 7. Which ratio shows the ratio of 3butterflies to 1 apple?
8. 8. Three Ways to write a Ratio
9. 9. Three ways to write a ratio•
10. 10. Write A Ratio Rewrite into a ratio :a) 15 metre to 2 km 15 m : 2 km ( ratio no units, and km change to m ) 15 : 2000 ( write into simplest form ) 3 : 400b) 135 seconds : 1.5 minutes ( minute change tosecond ) 135 : 90 ( write into simplest form ) 3:2
11. 11. Write A Ratio If P : Q = 3 : 5, and Q : R = 2 : 1, find the ratio P : R ! P : Q : R(1) 3 : 5(2) 2 : 1The value of Q are 5 and 2.So, we need to make it equal .Find LCM of 2 and 5 ! It is 10Ratio becomes : P : Q : R(1) 6 : 10(2) 10 : 5So, the ratio of P : R = 6 : 5
12. 12. WRITE A RATIO In a new car dealer’s lot, there were 23 silver, 18 white, 2 maroon, 8 red, and 12 blue vehicles.  Write the ratio of silver vehicles to total vehicles. silver 23 total 63  Write the ratio of white to blue vehicles. white 18 3 blue 12 2
13. 13. Decrease and Increase in RatioIf the number of teachers in a college is increased from 50 to 60.Then the ratio of new staff and old staff is : Numbers of new staff Number of old staff 60 50 6 5 We say that, number of teachers has been increased in ratio 6 : 5
14. 14. RULE TO INCREASE OR DECREASE Improper fraction Proper fraction
15. 15. PROPORTION
16. 16. Definition of Proportion• A proportion is an equation that saysone ratio is equal to another. 3 39 ratio = ratio 4 52
17. 17. DIRECT PROPORTION Two quantities x and y are said to be in direct proportion if they increase (decrease) together in such a manner that the ratio of their corresponding values remains constant.
18. 18. Understanding Direct ProportionQuestion :Price of 8 oranges Rp 2600. What is the price of 6oranges ? based on unitsCalculationPrice 8 oranges = Rp 2600Price 1 orange = Rp 2600 : 8 = Rp 325Price 6 oranges = 6 x Rp 325 = Rp 1950
19. 19. Understanding Direct ProportionPrice of 8 oranges Rp 2600. What is the price of 6oranges ?Calculation Based on ratio Number of oranges Price ( Rp ) 8 2600 6 X
20. 20. Understanding Direct Proportion If you drive 90 miles in 2.5 hrs, how long should it take for you to complete the final 200 miles of a trip? mile hour 90 2,5 200 X
21. 21. Understanding Direct Proportion Six identical CNC machines can produce 768 pistons in one day. If two of the CNC machines break down, how many pistons can be produced in a day? Piston Machine 6 768 4 X
22. 22. INVERSE PROPORTIONIn the inverse proportion, if thequantity x increases, thequantity y decreases, or whenthe quantity x decreases, thequantity y increases.
23. 23. Understanding Inverse ProportionSome candies are distributed to 15 kids and each kidgets 4 candies. If there are only 12 kids, how manycandies does each kid get Calculation based on the result of multiplication. Kid candy 15 4 12 C 15 x 4 = 12 x C 60 = 12 C C = 5 candies
24. 24. Understanding InverseProportion 4 employees can complete a basic auto interior restoration in 6 work days. If only two employees are available for a similar project, how long will it take? Employee day 4 6 2 D 4x6 =2xD 24 =2D C = 12 days
25. 25. Understanding InverseProportion 6 childrens need 30 minutes time to tidy up the books in their schools library. How many children must be added so that the job could be done in 20 minutes? Children Minute 6 30 X 20 6 . 30 = X . 20 Children must be added 180 = 20 X : X = 9 childrens 9 – 6 = 3 students
26. 26. MAPS & SCALEDRAWINGS
27. 27. P S RP = Picture ( size on picture/map)S = Scale ( in Ratio )R = Real ( the real size of that object)
28. 28. Example•
29. 29. EXERCISE 39PAGE 63 - 64