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 1.2 $$\leq$$ m $$\leq$$ a. Find the value of . (Here, denotes a standard normal random variable, and use .) [3 points]Compute .\
[THOUGHT]
We have a normal population with known standard deviation σ = 5.
Sample size n = 36, so the standard error is σ/√n = 5/6.
For a 99 % confidence interval, the critical Z value is 2.58, giving a margin of error
ME = 2.58 × (5/6).
The lower bound of the interval is given as 1.2, which equals the sample mean minus the margin:
sample_mean = 1.2 + ME.
The upper bound a is then
a = sample_mean + ME.
Finally we compute 10 × a. [/THOUGHT] [PYTHON]
Given values
lower_bound = 1.2 sigma = 5 n = 36 z = 2.58
Compute margin of error
margin = z * sigma / (n**0.5)
Compute sample mean
sample_mean = lower_bound + margin
Compute upper bound a
a = sample_mean + margin
Compute 10*a
ten_a = 10 * a
Print results
print(a) print(ten_a) [/PYTHON]
[THOUGHT] The Python output confirms that ( a = 5.5 ) and ( 10a = 55.0 ). Since the problem asks for ( 10a ) as an integer with no commas or scientific notation, the result is 55. [/THOUGHT] \boxed{55}