An experiment:  growth of wheat during the winter.  Average temperature (in °C) of the soil at a depth of 8 cm;   days necessary for sprouting: 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5;     40, 36, 32, 27, 23, 19, 19, 20 linear regression (without fixed point):  y = -6.4*x+70

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