Question

# Using extensive data compiled from their manufacturing records, it has historically taken 16 minutes to complete...

Using extensive data compiled from their manufacturing records, it has historically taken 16 minutes to complete the assembly of each FC340M-VB fire extinguisher.

...recently retooled their production line in an attempt to improve the operation’s overall efficiency and assembly time. After the retooling was complete, the quality control inspector took a random sample of n = 25 FC340M-VB fire extinguishers from the new production line and took note of the amount of time it took to assemble each one. The sample mean assembly time was 15.20 minutes, and the sample standard deviation was 2.53 minutes.

Can the quality control inspector reasonably conclude that the retooling of the production line has significantly changed the average assembly time for the FC340M-VB fire extinguisher? Do a complete and appropriate hypothesis test, using a significance level of .02.

Step 1 (Hypotheses)

H0:    (Click to select)   x-bar   n   s   π   p   μ   σ      (Click to select)   =   ≠   ≤   >   ≥   <

HA:    (Click to select)   μ   x-bar   π   p   σ   s   n      (Click to select)   =   ≠   ≤   >   ≥   <

Step 2 (Decision rule)

Using only the appropriate statistical table in your textbook, the critical value for rejecting H0 is   (Click to select)   +   -   ±   . (report your answer to 3 decimal places, using conventional rounding rules)

Step 3 (Test statistic)

Using the sample data, the calculated value of the test statistic is   (Click to select)   +   -   ±   . (report your answer to 2 decimal places, using conventional rounding rules)

Step 4 (Evaluate the null hypothesis)

Should the null hypothesis be rejected?    (Click to select)   yes   no

Step 5 (Practical conclusion)

Can the quality control inspector reasonably conclude that the retooling of the production line has significantly changed the average assembly time for the FC340M-VB fire extinguisher?    (Click to select)   yes   no

No, we can't conclude that the retooling of the production line has significantly changed the average assembly time for the FC340M-VB fire extinguisher because tit is not significant and there is not enough evidence to support the claim

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