Given the actual data below what is the forecast for period

Given the actual data below, what is the forecast for period 6, using a four-period weighted moving average with weights of .1, .2, .3 and .4 (greater weight towards more recent time)?

Period              Demand

            1                       19

            2                       20

            3                       18

            4                       19

            5                       17

Solution

fore cast for period 6 = 0.4*17+0.3*19+0.2*18+0.1*20

= 6.8+5.7+3.6+2

=18.1