Download Stat 302 Statistical Methods 1 (2) Question 1: A computer software

Stat 302 Statistical Methods 1
(2)
Question 1:
A computer software package was used to calculate some numerical summaries of a sample
of data. The results are displayed here:
Variable : X , N=? , Mean=? , SE mean= 2.05 , StDev=10.25 , Variance=?
Sum= 3761 , Sum of squares=?
(a)Fill in the missing quantities
(b)What is the estimate of the mean of the population from which this sample was drawn?
Answer 1:
(a)N=25 Mean=150.47
(b)150.468
Variance=105.06
SS=2521.5
Question 2:
A manufacturer produces piston rings for an automobile engine. It is known that ring
diameter is normally distributed with standard deviation 0.001 millimeters. A random
sample of 15 rings has a mean diameter 74.036 millimeters.
(a)Construct a 99% two sided confidence interval on the mean piston ring diameter.
(b)Construct a 99% lower confidence bound on the mean piston ring diameter. Compare the
lower bound of this confidence interval with the one in part (a).
Answer 2:
(a)[74.0353 , 74.0367]
(b)[74.035 , infinity]
Question 3:
A postmix beverage machine is adjusted to release a certain amount of syrup into a
chamber where it is mixed with carbonated water. A random sample of 25 beverages was
found to have a mean syrup content 1.10 fluid ounce and a standard deviation of s= 0.015
fluid ounce. Find a 95% CI on the mean volume of syrup dispensed.
Answer 3:
[1.094 , 1.106]
Question 4:
The percentage of titanium is an alloy used in aerospoace castings is measured in 51
randomly selected parts. The sample standard deviation is 0.37. Construct a 95% two sided
confidence intervals for standard deviation.
Answer 4:
[0.31 , 0.46]