5. The time series for this problem is stride length measured every 30 seconds for a runner on a treadmill moving at pace of 7 minutes per mile. Following are the ACF and PACF for the series. Briefly describe what model(s) may be suggested by these plots (and explain why). ACF 0.2 04 06 08 LAG PACF 02 04 06 08 0.0 T 1 I 1 I i I I 1 I 1 1 I | I I 1 1 1 I 1 = I I | 1 I 1 -1 I S | I I 1 | 1 I I I I 1 1 1 I = i I I I : 1 -] 1 I I I I 1 I I 1 LAG