StatisticsdrillPredicted value from a fitted line
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). Fit the least squares line and predict y when x = 11. Round to 2 decimal places.
What this problem teaches
Predictions are safest inside the range of x in the data. Outside it you are extrapolating.
A hint if you get stuck
Find b and a, then ŷ = a + b x. Keep b and a unrounded until the end.
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