In a random sample of 10 cell phones the mean full retail price was $528.40 and the standard deviation was $192.00. Further research suggests that the population mean is $428.43. Does the t value for the original sample fall between -t0.99 and t0.99

Respuesta :

To determine if the t-value for the original sample falls between -t0.99 and t0.99, we need to calculate the t-value for the original sample and compare it with the critical values provided by the t-distribution table.

Given:
- Sample size (\( n \)) = 10
- Sample mean (\( \bar{x} \)) = $528.40
- Population mean (\( \mu \)) = $428.43
- Standard deviation (\( \sigma \)) = $192.00

First, we need to calculate the standard error of the mean (\( SEM \)):

\[ SEM = \frac{\sigma}{\sqrt{n}} \]

\[ SEM = \frac{192.00}{\sqrt{10}} \]
\[ SEM \approx 60.733 \]

Next, we calculate the t-value using the formula:

\[ t = \frac{\bar{x} - \mu}{SEM} \]

\[ t = \frac{528.40 - 428.43}{60.733} \]
\[ t \approx 1.647 \]

Now, we compare the calculated t-value (1.647) with the critical values -t0.99 and t0.99. We'll consult the t-distribution table or use statistical software to find these critical values. For a two-tailed test with 9 degrees of freedom (since \( n - 1 = 10 - 1 = 9 \)), the critical t-values are approximately -2.262 and 2.262 for a 0.01 significance level (corresponding to the 99% confidence interval).

Since the calculated t-value (1.647) falls between -2.262 and 2.262, we can conclude that the t-value for the original sample does fall between -t0.99 and t0.99. Therefore, at the 99% confidence level, we fail to reject the null hypothesis and conclude that there is not enough evidence to suggest that the population mean differs significantly from the sample mean.





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