Answer:
u => 4,028
Step-by-step explanation:
To find the answer, we have the following formula:
u => m - t (alpha, n-1) * [sd / (n) ^ (1/2)]
where m is the mean.
where sd is the standard deviation.
where n is the sample size.
t is a parameter that depends on the confidence interval and the sample size.
alpha = 1 - ci
ci = 90% = 0.9
Therefore, alpha = 1 - 0.9 = 0.1.
n - 1 = 25 - 1 = 24
So it would come being t (0.1, 24), if we look in the table, which I will attach the value of t is equal to 1.318.
We know the rest of the values, m = 4.05; sd = 0.08; n = 25
u => 4.05 - 1,318 * [0.08 / (25) ^ (1/2)]
u => 4.028
Which means that the interval with a 90% confidence of the wall thickness measurement is:
u => 4.028
