hard · SAT Math

A marine biologist records the water temperature (x, in °C) and swimming speed (y, in cm/s) for 8 individual fish of the same species, then fits a line of best fit to the scatterplot. Fish: A B C D E F G H Temp (°C): 5 8 10 12 15 18 20 22 Speed (cm/s): 13 19 23 26 28.5 36 40 43 Line of best fit: y = 1.8x + 4, where x = water temperature in °C and y = predicted swimming speed in cm/s. For Fish E (temperature = 15°C, actual speed = 28.5 cm/s), does the line of best fit overestimate or underestimate the actual swimming speed, and by how much?

1. Underestimates by 2.5 cm/s
2. Overestimates by 2.5 cm/s
3. Overestimates by 31 cm/s
4. Underestimates by 1.5 cm/s

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