Question

For patients who have been given a diabetes test, blood-glucose readings are approximately normally distributed with mean 127 mg/dl and a standard deviation 10 mg/dl. Suppose that a sample of 4 patients will be selected and the sample mean blood-glucose level will be computed. Enter answers rounded to three decimal places.
According to the empirical rule, in 95 percent of samples the SAMPLE MEAN blood-glucose level will be between
the lower-bound of [BLANK] and the upper-bound of [BLANK]

Answer 1

Answer:

Between the lower-bound of 117 mg/dl and the upper bound of 137 mg/dl.

Step-by-step explanation:

Empirical Rule

The Empirical Rule states that, for a normally distributed random variable:

Approximately 68% of the measures are within 1 standard deviation of the mean.

Approximately 95% of the measures are within 2 standard deviations of the mean.

Approximately 99.7% of the measures are within 3 standard deviations of the mean.

Central Limit Theorem:

The Central Limit Theorem estabilishes that, for a normally distributed random variable X, with mean $\mu$ and standard deviation $\sigma$, the sampling distribution of the sample means with size n can be approximated to a normal distribution with mean $\mu$ and standard deviation $s = \frac{\sigma}{\sqrt{n}}$.

In this question:

Mean of 127, standard deviation of 10.

For the sample mean:

By the Central Limit Theorem, mean is 127, while the standard deviation is $s = \frac{10}{\sqrt{4}} = 5$

According to the empirical rule, in 95 percent of samples the SAMPLE MEAN blood-glucose level will be between?

By the Empirical Rule, within 2 standard deviations of the mean. So

127 - 2*5 = 117 mg/dl

127 + 2*5 = 137 mg/dl.

Between the lower-bound of 117 mg/dl and the upper bound of 137 mg/dl.