In a numerical table with \(10\) rows and \(10\) columns, each entry is either a \(9\) or a \(10.\) If the number of

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In a numerical table with \(10\) rows and \(10\) columns, each entry is either a \(9\) or a \(10.\) If the number of \(9s\) in the \(nth\) row is \(n - 1\) for each \(n\) from \(1\) to \(10,\) what is the average (arithmetic mean) of all the numbers in the table?

A. 9.45

B. 9.50

C. 9.55

D. 9.65

E. 9.70

Answer: C

Source: Official Guide