Consider a value to be significantly low if its z score is less than or equal to -2 or consider the value to be significantly high if its z score is greater than or equal to 2 9. ACT The ACT test is used to assess readiness for college. In a recent year, the mean ACI score was 21.1 and the standard deviation was 5.1. Identify the ACT scores that are significantly low or significantly high. 10. MCAT In a recent year, scores on the Medical College Admission Test (MCAT) had a mean of 25.2 and a standard deviation of 6.4. Identify the MCAT scores that are significantly low or significantly high.