Pregunta
- A tyre manufacturer wishes to investigate the tread
life of its tyres. A sample of 10 tyres driven 50,000
miles revealed a sample mean of 0.32 inch of
tread remaining with a standard deviation of 0.09
inch. Construct a
confidence interval for the
population mean. Would it be reasonable for the
manufacturer to conclude that after 50,000 miles
the population mean amount of tread remaining is
0.30 inch?
life of its tyres. A sample of 10 tyres driven 50,000
miles revealed a sample mean of 0.32 inch of
tread remaining with a standard deviation of 0.09
inch. Construct a
population mean. Would it be reasonable for the
manufacturer to conclude that after 50,000 miles
the population mean amount of tread remaining is
0.30 inch?
Ask by Ayala Grant. in Jamaica
Mar 21,2025
Solución de inteligencia artificial de Upstudy
Respuesta verificada por el tutor
Responder
The
confidence interval for the population mean tread remaining is approximately
to
inches. Since
inch falls within this interval, it is reasonable for the manufacturer to conclude that after 50,000 miles, the population mean tread remaining is
inch.
Solución
To construct a
confidence interval for the population mean, we can use the formula for the confidence interval:
where:
-
is the sample mean -
is the critical value from the standard normal distribution for a confidence level -
is the sample standard deviation -
is the sample size
Given:
- Sample mean (
) = 0.32 inch - Sample standard deviation (
) = 0.09 inch - Sample size (
) = 10
First, we need to find the critical value
for a
confidence level. The critical value for a
confidence level is typically 1.96.
Now, we can calculate the confidence interval using the formula above.
The confidence interval for the population mean is approximately
to
.
The
To determine if it would be reasonable for the manufacturer to conclude that after 50,000 miles the population mean amount of tread remaining is 0.30 inch, we need to check if the value 0.30 inch falls within the confidence interval.
Since 0.30 inch is within the confidence interval, it would be reasonable for the manufacturer to conclude that after 50,000 miles the population mean amount of tread remaining is 0.30 inch.
Respondido por UpStudy AI y revisado por un tutor profesional
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Bonus Knowledge
To construct a
confidence interval for the population mean, we can use the formula:
where
is the standard deviation,
is the sample size, and
is the t-value for 9 degrees of freedom (since
). From the t-table, the
value for
confidence and
degrees of freedom is approximately
.
Calculating the margin of error:
Thus, the confidence interval is:
Given this interval, it does include
, which means it would be reasonable for the manufacturer to conclude that the population mean amount of tread remaining after
miles is
inch.
Ever wondered how manufacturers conduct their tests? They often use rigorous protocols and statistical analyses to determine the durability and safety of products. By understanding the average wear and tear, they can design better products that meet safety standards while providing consumers with reliable information on usage.
In real-world applications, this kind of statistical analysis doesn’t just stop with tyres. Think about how it applies to everything from clinical trials for new medicines to understanding consumer Preferences. Companies use confidence intervals to gauge whether their products meet expectations, creating a more informed decision-making process that benefits both the manufacturer and the consumer.

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