(a) An engineer designs an improved light bulb. The previous design had an average lifetime of
1200 hours. The new bulb had a lifetime of 1200.2 hours, using a sample of 40,000 bulbs.
Although the difference is quite small, the effect was statistically significant. The explanation is
A. that new designs typically have more variability than standard designs.
B. that the mean of 1200 is large.
C. that the sample size is very large.
D. all of the above.
Here the sample size is large which results in the p-value being less. As a result, reject the null hypothesis, and the effect was thus statistically significant.
