Final answer:
In statistical terms, the z-score for a SAT math score of 720 is approximately 1.74, indicating a performance above the mean. A score of 1.5 standard deviations above the mean SAT score equates to about 692.5. To see who performed better relative to the others in the SAT or ACT, z-scores of both tests are compared, with the higher z-score indicating a relatively better performance.
Step-by-step explanation:
This question requires a statistical analysis to compare mean scores of two related samples and to interpret z-scores and their significance in the context of the SAT math section. We begin by computing a z-score for a given SAT math score, then we find what score corresponds to a certain number of standard deviations above the mean, and finally, we compare scores from two different standardized tests.
To calculate the z-score for an SAT score of 720, use the formula z = (X - μ) / σ, where X is the score, μ is the mean, and σ is the standard deviation. For μ = 520 and σ = 115, we get z ≈ (720 - 520) / 115 ≈ 1.74. The z-score of 1.74 means the score of 720 is 1.74 standard deviations above the mean.
A math SAT score that is 1.5 standard deviations above the mean is computed as 520 + 1.5(115) ≈ 692.5. This score is significantly higher than the average score and indicates a strong performance relative to the typical test-taker.
To determine who did better with respect to the test each person took, convert both SAT and ACT scores to their respective z-scores and compare these. For SAT: zSAT = (700 - 514) / 117 ≈ 1.59. For ACT: zACT = (30 - 21) / 5.3 ≈ 1.70. The person with the higher z-score performed relatively better. In this case, the student taking the ACT outperformed the one taking the SAT.