Percentage Problems

Percentage Problems

Remember: Percentage change

= (difference between original value and new value / original value) x 100

Percentage increase = (increased value - original value / original value) x 100

Percentage decrease = (original value - decreased value / original value ) x 100

Note

1) There is a huge difference between "decreased value" and "decrease in value" and between "increased value" and "increased in value".

for example : Initial value = 70

                       Final value = 90

it mean increased value is = 90
but increase in value is 20
and % increase = 90 -70 / 70  x 100  = 28.57%


2) If there is increased  of x/y in any value P then the increased value will be 
       P (1 + x/y)

3) If there is decrease of x/y in any value, then the decreased value will be
       P(1 - x/y)


Example 1  

Nishith is now 20 years old. Some years later his age will increased by 50% of himself. What will be the new age at that time?

Solution:

20(1 + 1/2 ) = 30 years        ( therefore 20 + 20 x 1/2 = 20 (1 + 1/2) )

Example 2

The average salary of purushottam in infosys is 20% less than that was in microsoft. If the salary of prurushottam in microsoft be rs 80,000 per month then what is the salary of purushottam in infosys? 

Solution:

20% = 1/5

so new salary = 80,000 ( 1 - 1/5)

                     = 80,000 x 4/5 = rs.64,000

Example 3

Which one of the following is greater 3/4, 7/8, 16/19, 13/15 ?

Solution:

3/4 = 75%

7/8 = 87.5%

16/19 = 84.21%

13/15 = 86.66%

so, 7/8 is the greatest fraction ( or rational number)