$4.$ Measuring the Forecast Accuracy for Monthly Lightning Strikes. The following time series data show the number of lightning strikes in Catahoula County for the most recent seven months.

Month $1234567$

Value $24132012192315$

a$.$ Compute MSE using the most recent value as the forecast for the next period. What is the forecast for Month $8?$

b$.$ Compute MSE using the average of all the data available as the forecast for the next period. What is the forecast for Month $8?$

c$.$ Which method appears to provide the better forecast?