A farmer is investigating whether using a new fertiliser will increase the yield of tomato plants. The farmer selects 40 tomato plants at random and gives them the new fertiliser. The crop mass, \(x \mathrm{~kg}\), of each of these 40 plants is recorded. The farmer selects a further 60 tomato plants at random and gives them a standard fertiliser. The crop mass, \(y \mathrm{~kg}\), of each of these 60 plants is recorded. The results are summarised as follows.
\(\sum x=168 \quad \sum x^{2}=720 \quad \sum y=228 \quad \sum y^{2}=900\)

Find a \(90 \%\) confidence interval for the difference in mean crop mass associated with each type of fertiliser.