1 The total project cost for a Trex deck ranges between $1,500 and $2,200 for a 250sf deck. 2  Trex Select of basic quality averages approximately $7/sf.  Trex Enhance of higher quality is approximately $8/sf.
When the hypothesized value is zero then there is a simple relationship between hypothesis testing and confidence intervals: If the interval contains zero then the null hypothesis cannot be rejected at the stated level of confidence. If the interval does not contain zero then the null hypothesis can be rejected.
The test statistic is called T. (This is not the same as the t test.) The statistic must be looked up in a table to find level of significance. The values of T range from 0 to 100. Unlike most tests, T must be less than or equal to the critical value to reject the null hypothesis.