In a random sample of adults aged 20-29, the middle 95% of the men are between 168 and 191 cm tall, and the middle 95% of the women are between 155 and 174 cm tall. The heights of each sex follow a normal distribution. Robert and Amanda are both 25 years old, and Robert is 12.7 cm taller than Amanda. Find their respective z-scores.

Thank you for posting the solution. I do have a question: The z-score of Robert is (1 - 1.645), which should have a negative sign -0.645. But you came up with his z-score as a positive number. Why?