A certain group of test subjects had pulse rates with a mean of 81.7 beats per minute and a standard deviation of 11.4 beats per minute. Use the range rule of thumb for identifying significant values to identify the limits separating values that are significantly low or significantly high. Is a pulse rate of 74.5 beats per minute significantly low or significantly high? Significantly low values are beats per minute or lower. (Type an integer or a decimal. Do not round.)
Solution
Step 1 ：Given that the mean pulse rate is 81.7 beats per minute and the standard deviation is 11.4 beats per minute.
Step 2 ：The range rule of thumb states that most values should fall within 2 standard deviations of the mean.
Step 3 ：We calculate the lower limit by subtracting 2 times the standard deviation from the mean: \(81.7 - 2 \times 11.4 = 58.9\) beats per minute.
Step 4 ：This means that pulse rates lower than 58.9 beats per minute are considered significantly low.
Step 5 ：Given a pulse rate of 74.5 beats per minute, we compare it with the lower limit.
Step 6 ：Since 74.5 beats per minute is higher than the lower limit of 58.9 beats per minute, it is not considered significantly low.
Step 7 ：\(\boxed{74.5 \text{ beats per minute is not significantly low}}\)
