IQ scores are measured with a test designed so that the mean is 120 and the standard deviation is 12. Consider the group of IQ scores that are unusual. What are the z scores that separate the unusual IQ scores from those that are​ usual? What are the IQ scores that separate the unusual IQ scores from those that are​ usual? (Consider a value to be unusual if its z score is less than minus2 or greater than​ 2.)What are the IQ scores that separate the unusual IQ scores from those that are​ usual?