Type 5

% Solved!

Type #5

4)    Increasing or decreasing a number by a given %

I have:  1 number

 I have: A given % increase or decrease

I need to find: The new value, after the % change has been applied.

Example:    a) What is $640.00 decreased by 10%?

                   b) What is $200.00 increased by 20%?

Key to Solving:

These questions are not much different from a type 2 question. You just need to think of the % as a new value.

a)     What is $640.00 decreased by 10%?

Step 1 – a 10% decrease is equal to 90% of the original value

Step 2 –       90    X  640.00 = $576.00  

                   100

b)    What is $200.00 increased by 20%?

Step 1 – a 20% increase is equal to 120% of the original value

Step 2 –       120    X  200.00 = $240.00  

                   100

Tricks to look out for.

Watch out for fractional percents like 3  1 %

                                                                  2

a) What is $360.00 increased by 3  1 %  ?

                                                                  2

Step 1 – a 3  1 %  increase is equal to 103.5% of the original value

                     2

Step 2 –       103.5   X  $360.00 = $372.60  

                   100

b)      What is 12 increased by 1 %  ?

    4

Note – a  1 %  increase is equal to 100.25% of the original value. It is a

                4    

                       quarter of a percent, not a quarter.

ý  Wrong! 125   X  $12 = $15.00   

                   100

þ Right!   100.25   X  $12 = $12.03