1. **Problem Statement:**
We are given a widget weight distribution and asked to use the Empirical Rule to find:
a) The interval containing 95% of the weights.
b) The percentage of weights between 48 and 63 ounces.
c) The percentage of weights below 68 ounces.
2. **Empirical Rule:**
For a normal distribution:
- About 68% of data lies within 1 standard deviation ($\sigma$) of the mean ($\mu$).
- About 95% lies within 2 standard deviations.
- About 99.7% lies within 3 standard deviations.
3. **Assumptions:**
Since the problem does not provide mean or standard deviation explicitly, we infer from the values given:
- The interval 48 to 63 likely corresponds to $\mu - \sigma$ to $\mu + \sigma$.
- The value 68 is likely $\mu + 2\sigma$.
4. **Step a) Find the 95% interval:**
Using the Empirical Rule, 95% of weights lie between $\mu - 2\sigma$ and $\mu + 2\sigma$.
Given $\mu + 2\sigma = 68$ and $\mu + \sigma = 63$, we find $\sigma$:
$$
\sigma = 68 - 63 = 5
$$
Then $\mu = 63 - \sigma = 63 - 5 = 58$
So the 95% interval is:
$$
[\mu - 2\sigma, \mu + 2\sigma] = [58 - 2(5), 58 + 2(5)] = [48, 68]
$$
5. **Step b) Percentage between 48 and 63:**
48 is $\mu - 2\sigma$ and 63 is $\mu + \sigma$.
From the Empirical Rule:
- Between $\mu - 2\sigma$ and $\mu + 2\sigma$ is 95%.
- Between $\mu - \sigma$ and $\mu + \sigma$ is 68%.
We want between $\mu - 2\sigma$ and $\mu + \sigma$.
This is the sum of:
- From $\mu - 2\sigma$ to $\mu - \sigma$: about 13.5% (half of the 27% outside 68% range)
- From $\mu - \sigma$ to $\mu + \sigma$: 68%
So total:
$$
13.5\% + 68\% = 81.5\%
$$
6. **Step c) Percentage below 68:**
68 is $\mu + 2\sigma$.
From the Empirical Rule, 95% of data lies between $\mu - 2\sigma$ and $\mu + 2\sigma$.
Since the distribution is symmetric, the percentage below $\mu + 2\sigma$ is:
$$
50\% + 47.5\% = 97.5\%
$$
(50% below mean + 47.5% between mean and $\mu + 2\sigma$)
**Final answers:**
a) 95% of widget weights lie between **48 and 68** ounces.
b) Percentage between 48 and 63 ounces is **81.5%**.
c) Percentage below 68 ounces is **97.5%**.
Empirical Rule 06B967
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