QUESTION IMAGE
Question
not everyone pays the same price for the same model of a car. the figure illustrates a normal distribution for the prices paid for a particular model of a new car. the mean is $21,000 and the standard deviation is $1000. use the 68 - 95 - 99.7 rule to find what percentage of buyers paid between $21,000 and $22,000. the percentage of buyers who paid between $21,000 and $22,000 is % (type an exact answer.)
Step1: Recall the 68 - 95 - 99.7 Rule
The 68 - 95 - 99.7 Rule states that for a normal distribution:
- Approximately 68% of the data lies within \(1\) standard deviation (\(\mu\pm\sigma\)) of the mean.
- Approximately 95% of the data lies within \(2\) standard deviations (\(\mu\pm2\sigma\)) of the mean.
- Approximately 99.7% of the data lies within \(3\) standard deviations (\(\mu\pm3\sigma\)) of the mean.
Step2: Analyze the range
Given \(\mu = 21000\) and \(\sigma=1000\). The range \(21000\) to \(22000\) is \(\mu\) to \(\mu + \sigma\).
Since the normal distribution is symmetric about the mean, the percentage of data within \(\mu-\sigma\) and \(\mu+\sigma\) is 68%. The percentage of data from \(\mu\) to \(\mu+\sigma\) is half of the percentage of data from \(\mu - \sigma\) to \(\mu+\sigma\).
Step3: Calculate the required percentage
We know that \(P(\mu-\sigma<X<\mu+\sigma)=68\%\). Then \(P(\mu<X<\mu + \sigma)=\frac{68\%}{2}\)
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