The mean for a data set is 45. The z-score for data point a is 0. The z-score for data point b is 0.2. What are the possible values for data points a and b?
z-score = [data point - average] / standard deviation.
If the z-score for data point a is 0, a must be the average, which is 45.
The value of b can't be determined unless you know the standard deviation.