As an owner of a business, having a consistent level of sales is important. Prior to the recession that started in 2007, the standard deviation of the sales of a local business was $475. In a sample of 31 weeks since the start of the recession, sales have averaged $6800 per week with a standard deviation of $880. When testing the hypothesis (at the 5% level of significance) that the variance is higher than it was pre-recession, what is the test statistic? (please round your answer to 2 decimal places)