The addition of a new accelerator is claimed to decrease the drying time of latex paint by more than 4%. Several test samples were conducted with the following percentage decrease in drying time. Assume that the percentage decrease in drying time is normally distributed.
| 5.1 |
6.4 |
3.5 |
5.9 |
3.6 |
2.5 |
3.1 |
4.4 |
(a) Find the 95% confidence interval for the true mean decrease in the drying time based on this sample. (Give your answers correct to two decimal places.)