Final answer:
A score of 120 is one standard deviation below the mean of 150 on a test with a standard deviation of 30.
Step-by-step explanation:
The score that is 1 standard deviation below the mean is found by subtracting the standard deviation from the mean. In the context of this normal distribution of test scores, with a mean of 150 and a standard deviation of 30, we calculate the score one standard deviation below the mean as follows:
Score = Mean – Standard Deviation = 150 – 30 = 120
This calculation indicates that a score of 120 is one standard deviation below the mean on this test.