StatisticsdrillSample covariance
A statistics problem from Statisticsdrill. Solve it with one answer box, with a fresh sample on every attempt and the worked steps and spreadsheet function in the answer, and it is checked the moment you submit.
The task
Data on monthly ad spend and sales at regional stores (x = Ad spend ($k), y = Sales ($k)): (9, 87.8), (10, 98.7), (6, 81.3), (12, 99.1), (15, 111.9), (6, 78.6). What is the sample covariance of x and y? Round to 2 decimal places.
What this problem teaches
The formula: s_xy = Σ(x - x̄)(y - ȳ) / (n - 1).
A hint if you get stuck
s_xy = Σ(x - x̄)(y - ȳ) / (n - 1). Its sign matches the direction of the relationship.
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