 Solution

ID: past-exam-of-the-mathematical-and-computational-biology-course-of-the-university-of-cambridge/2025/paper-1/3/a/solution

The vector of column sample means is

\overset{x}{ˉ} = (1, 3, 2)

. Subtract it from each observation. The centred data matrix, with cell types in the original order, is

X_{c} = - 1 - 1 - 1 3 - 3 111 - 2 - 2 22 .

Each column now has sample mean zero.

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