Percentage change, MATHSWATCH CLIP
                                    109
               profit and loss      GRADE
                                    3
 PERCENTAGE INCREASE OR 
                DECREASE
                  Percentage change, MATHSWATCH CLIP
                                                      109
                      profit and loss                 GRADE
                                                      3
 Percentage increase or decrease
  You will be given two amounts - an original amount and a 
     new amount
  Actual change = difference between the amounts
                                               actual change
    Percentage change (increase/decrease) =                   × 100%
                                               original amount
                  Percentage change, MATHSWATCH CLIP
                                                       109
                       profit and loss                 GRADE
                                                       3
 Example
    A baby weighs 3.5 kg at birth. After 6 
    weeks the baby’s weight has increased to 
    4.2 kg.
          What is the baby’s percentage increase in weight?
               The actual increase = 4.2 kg – 3.5 kg
                                    = 0.7 kg
               The percentage increase =    0.7 × 100% 
                                            3.5
                                         = 20%
                  Percentage change, MATHSWATCH CLIP
                                                        109
                       profit and loss                  GRADE
                                                        3
 Example
                               All t-shirts were 
                                £24 now only 
                                    £18! 
                      What is the percentage decrease?
       The actual decrease = £24 – £18 =      £6
                                       6 1
       The percentage decrease =      24 × 100% = 25%
                                         4
                        Percentage change, MATHSWATCH CLIP
     Difficulty                                                           109
           *                  profit and loss                             GRADE
                                                                          3
      A computer accessories shop increased the price of one of its printers from £80 
      to £100. Find the percentage increase in price.
                                                                         0
                      0                                                0
                    8                                               £1
                   £
              Original Price                                       New Price
                                         change                           In this case the 
        Percentage change =         original quantity     x 100            change is an 
                                                                            increase.  
                                          increase  
        Percentage increase =         original quantity    x 100
                                        20  
         Percentage increase =         80   x 100 = 25%