Answer :
Final answer:
The correct answer is A. To find the proportion of healthy adults with body temperatures below 97.8 degrees, we can use the normal distribution and the given information of sample mean, sample standard deviation, and sample size. By calculating the z-score and looking it up in the z-table, we can determine the proportion.
Explanation:
The question asks for the proportion of healthy adults expected to have body temperatures below 97.8 degrees. To find this, we need to use the normal distribution and the given information. Since body temperature follows a normal distribution, we can use the sample mean and sample standard deviation to estimate the population mean and standard deviation.
The z-score for a temperature below 97.8 degrees can be calculated as (97.8 - sample mean) / (sample standard deviation / sqrt(sample size)). By looking up the z-score in the z-table, we can find the proportion of temperatures below 97.8 degrees.
Using the given information of a sample mean of 98.4, sample standard deviation of 0.3, and a sample size of 20, we can calculate the z-score. The z-score is (97.8 - 98.4) / (0.3 / sqrt(20)) which equals -1.897. Looking up this z-score in the z-table, the proportion of temperatures below 97.8 degrees is approximately 0.029.