In N(2, 4) the mean is , the standard deviation is . Two standard deviations left of the mean is . The is when Z = (Z-score on standard normal curve). Two standard deviations right of the mean is . This is when Z = . (Z-score on standard normal curve). In the formulas X = Z and Z = X The value of X gives The value of Z gives The value of gives The value of gives The value of Z gives The value of X gives The value of X gives The value of Z gives