PERCENTAGE CHANGE IN A QUANTITY
To find the percentage change in a quantity, to find the percentage change in a quantity, write the change in the quantity as the numerator and the original quantity as the denominator, and then multiply the fraction by 100.
Change in the quantity
Percentage Change = ----------------------- X 100
Original quantity
Example.1) If the number of Kangaroo in Australia was 1500 in the year 2009 and 2000 in the year 2010 then an increase in the number of kangaroos = 2000 – 1500 = 500
So, percentage change ( or increase )
500
= ---------- X 100
1500
100
= ----------- = 33.33 % (Ans.)
3
If a quantity decreased by x%
x
New quantity = ( 1 - -------- ) X original quantity
100
New quantity
Original quantity = ----------------------------
x
( 1 - -------- )
100
If a quantity increased by x%
x
New quantity = ( 1 + -------- ) X original quantity
100
New quantity
Original quantity = --------------------------
x
( 1 + -------- )
100