A concrete manufacturer wanted to test the durability of two different types of reinforcements to its concrete: rebar and fiber. Employees who work in the research and development department cast 6 different sizes of concrete, making one of each size with rebar and one of each size with fiber. Then, the employees put the concrete under a steadily increasing amount of stress and measured the time it took for stress cracks to first appear in each type of concrete. The results (in minutes) are shown in the following table. Note: d = ( Rebar Fiber ) Rebar Fiber 15 9 16 14 18 10 19 16 20 21 11 13 Assume that both of the populations are normally distributed. At the 0.01 level of significance, is there sufficient evidence to show that there is a change in average amount of time until stress cracks appear between rebar and fiber? Use the test statistic 1.68 and the critical values 4.032 to draw a conclusion and interpret the results of this hypothesis test. Select the correct answer below: Reject the null hypothesis. There is sufficient evidence to show that there is a change in average amount of time until stress