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PROPORTION. I. R A T I O EXAMPLES : 1. 40 cm 60 cm We can say that the ratio of length to width is 60 : 40 = 3 : 2. 2. Given two rectangle the first has length 12 cm and width 9 cm the second has length 15 cm and width
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I. R A T I O EXAMPLES : 1. 40 cm 60 cm We can say that the ratio of length to width is 60 : 40 = 3 : 2
2. Given two rectangle the first has length 12 cm and width 9 cm the second has length 15 cm and width 12 cm. find the ratio of : a. Perimeter b. the area
ANSWER : Perimeter = 2 ( length + width ) P = 2 ( l + w ) The area = length x width A = l x w
So that : The ratio of perimeter is 2 ( 12 + 9 ) : 2 ( 15 + 12 ) 2 x 21 : 2 x 27 21 : 27 7 : 9
The ratio of area is : 12 x 9 : 15 x 12 9 : 15 3 : 5
SCALED DRAWINGS DISTANCE ON THE MAP SCALE THE REAL DISTANCE
DISTANCE ON THE MAP THE REAL DISTANCE SCALE = THE REAL DISTANCE = DISTANCE ON THE MAP DISTANCE ON THE MAP SCALE = SCALE x THE REAL DISTANCE
EXAMPLES : 1. The distance between Jakarta and Bandung is 180 km, if distance on the map is 12 cm find the scale !!
ANSWER : Real distance = 180 km = 18,000,000 cm Scale = distance on the map : real distance = 12 : 18,000,000 = 1 : 1,500,000 The scale of the map is = 1 : 1,500,000
2. The distance Surabaya and jakarta is 360 km, find the distance on the map if the scale is 1 : 2,400,000 !
ANSWER : Real distance = 360 km = 36,000,000 cm Scale = 1 : 2,400,000 = Distance on the map = scale x real distance 1 2,400,000
1 = 360 : 24 = 15 Distance on the map = 15 cm Distance on the map = X 36,000,000 2,400,000
3. Distance between Depok and Bogor on the map is 4 cm. find the real distance if the scale on the map is 1 : 750,000
Distance on the map Real distance = Scale THE SOLUTION : = = 4 x = 3,000,000 = 30 km Distance between Depok and Bogor is 30 km 4 1 750,000 750,000 1
PHOTOS AND SCALED MODELS Examples : 1. a photo has length 12 cm and width 8 cm if the length to be 9 cm find its width ! Answer : = 4x = 24 = = x = 6 l of big photo w of big photo l of small photo w of small photo 12 8 4 8 9 x 3 x
12 8 9 X = 12x = 72 x = 6 width of foto is 6 cm
2.A hotel has length 32 m and height 80 m if height on the photo is 10 cm, find : a. length hotel on the photo b. scaled. = answer : a. 32 m = 3200 cm 800x = 320 80 m = 8000 cm x = 4 so, length hotel on the photo is 4 cm 3200 8000 10 x
Distance on the map Realdistance b. Scale = = = So , Scale = 1 : 800 10 8000 1 800
DIRECT PROPORTION EXAMPLES : 1. the price of 3 mathematics books is Rp 60,000.00 , if Joko buys 7 books, how many rupiahs must Ali pays for ? and, how many rupiahs will Ali pay for if he buy only 2 books ?
ANSWER : 3x = 7 x 60000 = 3x = 420000 x = 140000 So, The price of 7 books is Rp 140,000.00 3 60000 7 x
1 3 3 60000 x 60000 x Next : = 3x = 120000 x = 40000 So, the price of 2 books is Rp 40,000.00 or: find price of 1 book = 3x = 60000 x = 20000 7 books 7 x 20000 = 140000 3 books 2 x 20000 = 40000 2
INVERSE PROPORTION Examples 1. Ita has some money she wants to buy pencils. If she wants to buy then the price is Rp 2,000.00 , she will get 6 pencil. How many pencils will Ita get, if she wants to buy that the price of pencil is Rp 1,500.00 ? answer = 15x = 120 x = 8 so, ita get 8 pencil 2000 x 6 1500