If the probability limit for a series of measurements is increased from 95% to 9
ID: 3206394 • Letter: I
Question
If the probability limit for a series of measurements is increased from 95% to
99%,
a) how will the “Student’s t” factor be affected (higher, lower, or the same)?
Give your reasoning.
b) how will the confidence interval for a single value be affected? Give your
reasoning.
c) how will the confidence interval for the mean be affected? Give your
reasoning.
If 10 sets of randomly selected glass beads are weighed instead of 5 sets of
randomly selected glass beads,
a) how will the estimate of the standard deviation of the mass be affected
(higher, lower, or the same)? Give your reasoning.
b) how will the “Student’s t” factor be affected? Give your reasoning.
c) how will the confidence interval for the mean be affected? Give your
reasoning.
Explanation / Answer
1.a. As we increase the 95% to 99% t value will always increase for any df.
b. As t increases confidence becomes wider.
c. For mean=130.5, sd=32.4 and n=30 we get confidence interval becomes wider
99% confidence interval: 114.19486 x 146.80514 95% confidence interval: 118.40164 x 142.59836 90% confidence interval: 120.44898 x 140.55102