Ari is reading a journal article about a standardized mood scale. The method section describes the μ = 42, and then goes on to mention that a score of 40 corresponds to a z = XXXXXXXXXXnegative . 50)...

Ari is reading a journal article about a standardized mood scale. The method section describes the μ = 42, and then goes on to mention that a score of 40 corresponds to a z = - . 50 (negative . 50). For this mood scale, what is the population standard deviation? (hint: draw the distribution)