The y-intercept is the starting point. Since the temperature started at -7, we know that b in y = mx + b has to be -7. m is the slope which in our case is 3 because the temperature is changing every hour. So, because the temperature is going up, it's +3. Our equation should be y = 3x - 7.
To answer this question you will need to calculate the mean for each of the Shifts and then compare those means to the mean of all the data given. I have attached a picture of the means for each shift and the population mean (all the data).
Shift 1 is the closest to the population mean. It is 37.4, and the population mean is 35.9.
Sorry about that i didnt read the question properly
The correct answer would be -8-i! :)