True or False: 1)A quality control engineer is interested in the mean length of sheet insulation being cut automatically

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True or False:
1)A quality control engineer is interested in the mean length of
sheet insulation being cut automatically by machine. The desired
length of the insulation is 12 feet. It is known that the standard
deviation in the cutting length is 0.15 feet. A sample of 70
cut sheets yield a mean length of 12.14 feet. This sample will be
used to obtain a 99% confidence interval for the mean length cut by
machine. The critical value to use in obtaining the confidence
interval is 2.58.
2)A random sample of 50 provides a sample mean of 31 with a
standard deviation of s = 14. The upper bound of
a 90% confidence interval estimate of the population mean is
34.32.
3)In forming a 90% confidence interval for a population mean
from a sample size of 22, the number of degrees of freedom from
the t distribution equals 22.
4)The value that separates a rejection region from a
non-rejection region is called the level of significance.
5)The t distribution is used to construct
confidence intervals for the population mean when the population
standard deviation is unknown.
6)The statement of the null hypothesis always contains an
equality.