Testing for 1% significant level

3. Four different brands of batteries were tested for length of operating time. The researchers were interested to see if there is a difference in the average operating time. Brand X Brand Y Brand W Brand Z 26.0 29.1 30.0 28.2 28.5 28.8 26.3 24.1 27.3 27.6 29.2 27.5 25.9 28.1 27.1 28.4 28.2 27.0 29.8 30.0 Test at a 1% significance level