In a particular country, large numbers of ducks live on lakes \(A\) and \(B\). The mass, in kg, of a duck on lake \(A\) is denoted by \(x\) and the mass, in kg, of a duck on lake \(B\) is denoted by \(y\). A random sample of 8 ducks is taken from lake \(A\) and a random sample of 10 ducks is taken from lake \(B\). Their masses are summarised as follows.
$$\Sigma x = 10.56 \quad \Sigma x ^ { 2 } = 14.1775 \quad \Sigma y = 12.39 \quad \Sigma y ^ { 2 } = 15.894$$
A scientist claims that ducks on lake \(A\) are heavier on average than ducks on lake \(B\).
- Test, at the \(10 \%\) significance level, whether the scientist's claim is justified. You should assume that both distributions are normal and that their variances are equal.
A second random sample of 8 ducks is taken from lake \(A\) and their masses are summarised as
$$\Sigma x = 10.24 \quad \text { and } \quad \Sigma ( x - \bar { x } ) ^ { 2 } = 0.294$$
where \(\bar { x }\) is the sample mean. The scientist now claims that the population mean mass of ducks on lake \(A\) is greater than \(p \mathrm {~kg}\). A test of this claim is carried out at the \(10 \%\) significance level, using only this second sample from lake \(A\). This test supports the scientist's claim. - Find the greatest possible value of \(p\).
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