Final answer:
The percentage at which quarterly ALARA alert levels are set cannot be specified without further context. 'Effective dose - 50%' refers to the dose causing a significant response in 50% of subjects. For radiation shielding calculations, including the required thickness of lead to achieve a certain level of absorption, specific models and further data are necessary.
Step-by-step explanation:
The concept of ALARA, which stands for "As Low As Reasonably Achievable," pertains to minimising radiation exposure and dose. However, without more context or a standard referencing system, it is not possible to confidently state the percentage at which quarterly ALARA alert levels are set, as it can vary depending on the institution, the regulatory body, or the specific application in which ALARA principles are being applied.
In response to the provided reference information, the term "Effective dose - 50%" generally refers to the dose that results in a significant response in 50% of subjects (Option D). This definition can be commonly found in pharmacology, toxicology, or radiation therapy when discussing the effects of a substance or the efficacy of a treatment.
The confusion between Type I and Type II errors in statistical hypothesis testing is addressed using the context of a drug's cure rate. A Type I error occurs when a patient believes the cure rate for a drug is less than 75 percent when it actually is at least 75 percent. A Type II error occurs when a patient believes the experimental drug has at least a 75 percent cure rate when it actually has a cure rate that is less than 75 percent.
To calculate the thickness of lead needed to absorb all but 0.100% of the rays from a radioactive source, if initially 1.50 cm of lead absorbs 90.0%, a mathematical model such as the exponential decay model could be used. Such calculations typically require the use of logarithms, and further information about the attenuation properties of lead for the specific kind of radiation involved would be necessary to provide an accurate answer.