Decrease Percent
When a quantity shrinks (gets smaller), then we can compute its Decrease Percent:
( Original amount - New amount)
Decrease %= ----------------------------------- x 100
Original amount
|
Note: When you compute percent decrease,
you always compare how much a quantity has changed to the original amount.
Examples :
1) Find the decrease % of a) $80 to $60 b) $155 to $130
a) $80 to $60
Solution :
Original amount= $80
Net amount = $60
( Original amount - New amount)
Decrease %= ----------------------------------- x 100
Original amount
|
( 80 - 60)
Decrease %= ------------ x 100
80
|
= (20/80) x 100
= 0.25 x 100
So, Decrease % = 25
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b) $155 to $130
Solution :
Original amount= $155
Net amount = $130
( Original amount - New amount)
Decrease %= ----------------------------------- x 100
Original amount
|
(155 - 130)
Decrease %= ------------ x 100
155
|
= (25/155) x 100
= 0.16129 x 100
So, Decrease % = 16.129
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2) On Sunday 845 people went to the Zoo. On Monday only 169 people went. What is the per cent decrease in the people visiting the Zoo on Monday?
Solution :
Original amount = 845
New amount = 169
( Original amount - New amount)
Decrease %= ----------------------------------- x 100
Original amount
|
( 845 -169)
Decrease %= --------------- x 100
845
|
= (676/845) x 100
= 0.8 x 100
So, Decrease % = 80
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3) A man got 10% decrease in purchasing a machine . If the new price of the machine was $3000, find the original price of the machine.
Solution :
Decrease % = 10
New amount = $3000
Let original amount be $p.
( Original amount - New amount)
Decrease %= ----------------------------------- x 100
Original amount
|
( p - 3000)
10 % = ---------------------- x 100
p
|
Cross multiply
10p = (p - 3000) x 100
10p = 100p - 300,000
10p-100p = -300,000
-90p = - 300,000
So, p = 300,000/90
p = $3333.33
Percentage
• Conversion of Percentage to Fraction
• Conversion of Fraction to Percent
• Conversion of Percentage to Decimal
• Conversion of Decimal to Percent
• Find the Percentage of a given number
• What Percent is one number of another number
• Percentage as a comparison of two quantities
• Increase Percent
• Decrease Percent
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