Final answer:
Ali's z-score is calculated by comparing his marks to the mean and standard deviation of the class. His score is one standard deviation below the mean, resulting in a z-score of -1. However, this option is not listed among the choices, suggesting a need for problem clarification.
Step-by-step explanation:
To solve the problem of finding Ali's standardized score in the context provided, we first understand the relationship between Ali's marks, the class mean, and the standard deviation. The class mean is twice the standard deviation, and Ali's marks are equal to half of the mean. If we let σ represent the standard deviation, the mean (μ) would be 2σ, and Ali's marks would be σ.
The z-score is calculated using the formula z = (X - μ)/σ, where X is the value in question, μ is the mean, and σ is the standard deviation. Plugging in Ali's marks and the given relationships, we have z = (σ - (2σ)) / σ = -1. Hence, the standardized score in this scenario is -1, but this option is not available in the provided choices. Since this doesn't match any options, it would be best to review the problem for potential errors or reach out for clarification.