Question 4: A statistician is interested in studying the relationship between people's happiness (at 1-10 scale, 10 being the happiest) versus the time that they possessed their current cell phone (in months), and he believes that people's happiness can be explained by the time that they own their current cell phone. Suppose based on a random sample of 12 adults, he found correlation coefficient of -0.67, is there enough evidence to conclude there exist a negative correlation between people's happiness and the length of time they possess their current cell phone at a = 0.1 (If z-test use p-value method, if t-test use critical region method)