Assume that females have pulse rates that are normally distributed with a mean of 74 beats per min and a standard deviation of 12.5 beats per min. If 9 adults are randomly selected, find the probability that they have pulse rates with a mean less than 80 beats per min. Hint: Use the Central limit theorem. O 0.0749 O 1.44 O 0.5 O 0.9251

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**Understanding Probability Using the Central Limit Theorem**

**Problem Statement:**

Assume that females have pulse rates that are normally distributed with a mean of 74 beats per minute (bpm) and a standard deviation of 12.5 bpm.

If 9 adults are randomly selected, find the probability that they have pulse rates with a mean less than 80 bpm.

**Hint:** Use the Central Limit Theorem.

**Options:**
- O 0.0749
- O 1.44
- O 0.5
- O 0.9251

The Central Limit Theorem (CLT) states that the sampling distribution of the sample mean will be normally distributed if the sample size is sufficiently large (usually n > 30), regardless of the shape of the population distribution. However, for smaller sample sizes like 9, the population distribution should be normal.

To solve the problem:

1. **Determine the standard error (SE):**
   \[ SE = \frac{\sigma}{\sqrt{n}} \]
   where \(\sigma = 12.5\) bpm (standard deviation), and \(n = 9\) (sample size).

   \[ SE = \frac{12.5}{\sqrt{9}} = \frac{12.5}{3} = 4.17 \text{ bpm (approximately)} \]

2. **Calculate the z-score:**
   \[ Z = \frac{(\bar{x} - \mu)}{SE} \]
   where \(\bar{x} = 80\) bpm (sample mean we are comparing to), and \(\mu = 74\) bpm (population mean).

   \[ Z = \frac{(80 - 74)}{4.17} = \frac{6}{4.17} \approx 1.44 \]

3. **Find the probability:**
   Using standard normal distribution tables or a calculator, find the probability corresponding to \(Z \leq 1.44\).

   This yields the approximate probability of 0.9251.

Hence, the correct answer is:

- O 0.9251
Transcribed Image Text:**Understanding Probability Using the Central Limit Theorem** **Problem Statement:** Assume that females have pulse rates that are normally distributed with a mean of 74 beats per minute (bpm) and a standard deviation of 12.5 bpm. If 9 adults are randomly selected, find the probability that they have pulse rates with a mean less than 80 bpm. **Hint:** Use the Central Limit Theorem. **Options:** - O 0.0749 - O 1.44 - O 0.5 - O 0.9251 The Central Limit Theorem (CLT) states that the sampling distribution of the sample mean will be normally distributed if the sample size is sufficiently large (usually n > 30), regardless of the shape of the population distribution. However, for smaller sample sizes like 9, the population distribution should be normal. To solve the problem: 1. **Determine the standard error (SE):** \[ SE = \frac{\sigma}{\sqrt{n}} \] where \(\sigma = 12.5\) bpm (standard deviation), and \(n = 9\) (sample size). \[ SE = \frac{12.5}{\sqrt{9}} = \frac{12.5}{3} = 4.17 \text{ bpm (approximately)} \] 2. **Calculate the z-score:** \[ Z = \frac{(\bar{x} - \mu)}{SE} \] where \(\bar{x} = 80\) bpm (sample mean we are comparing to), and \(\mu = 74\) bpm (population mean). \[ Z = \frac{(80 - 74)}{4.17} = \frac{6}{4.17} \approx 1.44 \] 3. **Find the probability:** Using standard normal distribution tables or a calculator, find the probability corresponding to \(Z \leq 1.44\). This yields the approximate probability of 0.9251. Hence, the correct answer is: - O 0.9251
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