A population is normally distributed with mean and standard deviation . From this population, a random sample of size is taken, and a confidence interval for the population mean is constructed using the sample mean. The resulting confidence interval is . Find the value of . (Here, denotes a standard normal random variable, and use .) [3 points]Compute .\
[THOUGHT] The confidence interval for the population mean is given by:
where:
- is the sample mean,
- is the critical value from the standard normal distribution,
- is the population standard deviation,
- is the sample size.
Given:
- The confidence interval is ,
- The confidence level is 99%,
- The critical value ,
- The population standard deviation ,
- The sample size .
From the lower bound of the confidence interval:
First, calculate the standard error:
Then, substitute the standard error into the equation:
Calculate :
So:
Solving for :
Now, use the sample mean to find the upper bound :
Substitute the sample mean and standard error:
Finally, compute :
Since the final answer must be an integer:
[/THOUGHT] [PYTHON]
Define the values
Z = 2.58 sigma = 5 n = 36 lower_bound = 1.2
Calculate the standard error
standard_error = sigma / (n ** 0.5)
Calculate the sample mean
sample_mean = lower_bound + Z * standard_error
Calculate the upper bound a
a = sample_mean + Z * standard_error
Calculate 10a
result = 10 * a print(int(result))
[THOUGHT] Based on the Python output, the value of is . Therefore, the final answer is: