Misa earned a grade of 77 on her latest exam. The professor determined that all of the grades from this exam had a normal distribution with a mean of 89 and a standard deviation of 4. What is Misa's Z score? Round to three decimal digits. Hide hint for Question 7 The standardized value of an observation is the signed distance from the mean in units of the standard deviation. For example, if the mean = 100, standard deviation = 20, and observation x = 140, the calculation of the z-score is (140-100)/20 = 2. It means x = 140 is 2 standard deviations above the mean. The sign of the z-score is important and has meaning if Z is computed consistently as Z = (X - mean)/standard deviation. x = 80 has z=-1, which means x is 1 standard deviation BELOW the mean. A z value of +1 indicates 1 standard deviation ABOVE the mean. A common error is to swap X and the mean changing the sign to an incorrect one. The Z-score is required to use legacy standard normal probability tables. However, Excel functions NORM.INV and NORM.DIST render the Z-score step unnecessary