4. Administrators of a computer system are gathering data to try to explain the number of interruptions in their network. For a sample of 22 days, they measured the number of interruptions per day and the daily usage (measured by the average number of users of the system per hour of that day). Fit an appropriate regression model to predict the number of interruptions based on the usage. Assess the fit of the model. Formally assess whether usage is a significant predictor of mean interruptions, providing numerical justification (test statistic and P-value) for your conclusion. Carefully interpret what the estimated model tells you about how the expected number of interruptions changes as the daily usage changes. Predict the expected number of interruptions for a day that has 150 users per hour on average, using a point estimate and a 95% interval.