Respuesta :
The z-score of a certain data is calculated through the equation,
              z-score  = (x  - μ) / σ
where x is the data, μ is the mean and σ is the standard deviation.Â
Substituting,
             z-score = (28,000 - 34,000) / 4,000
               z-score = -1.5
              z-score  = (x  - μ) / σ
where x is the data, μ is the mean and σ is the standard deviation.Â
Substituting,
             z-score = (28,000 - 34,000) / 4,000
               z-score = -1.5