John Anderson is the operations manager for the call center 41-Cents-Joke -- a call center that tells a random, high-quality joke to the caller for the very reasonable rate of 41 cents -- has contacted you after hearing about your expertise in forecasting. Forecasting the number of incoming calls is crucial to the call center. With its current model, staffing is the single largest cost to the call center, and staffing levels are always set based on the forecasted number of calls. "For us", the manager explains, "good forecasting is not a joke!"

Staffing levels can be adjusted every 4 hours. The call center is operating from 6 pm to 6 am, so there are three 4-hour-blocks every day. The following data shows the number of incoming calls over these 4-hour-blocks for seven days: Data.

Note that the first period in the data (Period 1) is the 4-hour block from 6 pm to 10 pm.

Questions :