The linear trend was estimated using a time series with 20 time periods. The forecasted value for time period 21 is a. 162 b. 160 c. 122 d. 120

Thus the answer is : B (122)

Step-by-step explanation:

The time series was estimated using a time series with 20 time periods.

And the forecasted value for time period t after 20 time periods is 120 + 2t

For time period 21, the value of t is 1.

Hence, the forecasted value for time period 21 is 120 + 2*1 = 122

Thus the answer is : B (122)