Quincy claims that if 80 coats are sold, the outside temperature is likely to be about 42°F. Did Quincy make a reliable prediction? If not, what was his mistake? Yes. Quincy’s prediction is reliable. No. Quincy should have used the trend line to find the corresponding y value when x=80. No. Quincy should have used the trend line to find the corresponding x value when y=80. No. The prediction is extrapolated, so it is too far off the graph to be reliable.