A sample of automobiles traversing a certain stretch of high

A sample of automobiles traversing a certain stretch of highway is selected. Each automobile travels at a roubhly constant rate of speed, though speed does vary from auto to auto. Let x = speed and y = time needed to traverse this segment of highway. Would the sample correlation coefficient be closest to 0.9, 0.3, -3, or -0.9? Explain

Solution

As each automobile travels almost at the same speed with slight variation from autot to auto speed and time needed to traverse will be indirectly proportional.

i.e. when speed increases time decreases and vice versa.

Hence negative correclation of -0.9