7 A random sample of 8 swimmers from a swimming club were timed over a distance of 100 metres, once in an outdoor pool and once in an indoor pool. Their times, in seconds, are given in the following table.
| Swimmer | \(A\) | \(B\) | \(C\) | \(D\) | \(E\) | \(F\) | \(G\) | \(H\) |
| Outdoor time | 66.2 | 62.4 | 60.8 | 65.4 | 68.8 | 64.3 | 65.2 | 67.2 |
| Indoor time | 66.1 | 60.3 | 60.9 | 65.2 | 66.4 | 63.8 | 62.4 | 69.8 |
Assuming a normal distribution, test, at the \(5 \%\) significance level, whether there is a non-zero difference between mean time in the outdoor pool and mean time in the indoor pool.