Answer:
Lowest acceptable score = 121.3
Step-by-step explanation:
Mean test score (μ) = 115
Standard deviation (σ) = 12
The z-score for any given test score 'X' is defined as:
[tex]z=\frac{X-\mu}{\sigma}[/tex]
In this situation, the organization is looking for people who scored in the upper 30% range, that is, people at or above the 70-th percentile of the normally distributed scores. At the 70-th percentile, the corresponding z-score is 0.525 (obtained from a z-score table). The minimum score, X, that would enable a candidate to apply for membership is:
[tex]0.525=\frac{X-115}{12}\\X=121.3[/tex]
