Question

From a recent production run of compact fluorescent (CF) bulbs, you select a random sample of 10 bulbs. Using an accelerated bulb life simulation, you find that the average life for the bulbs in the sample is 2440 hours, with a sample standard deviation of 60 hours. Use these sample results to test, at the 5% significance level, the null hypothesis that the average life for the full population—the entire production run—of bulbs is pre- cisely 2500 hours, no more and no less. Report your con- clusion and explain.

Answer 1

Here claim is that the average life for the full population—the entire production run—of bulbs is pre- cisely 2500 hours, no more and no less.

So hypothesis here is vs

As n<30 and population standard deviation not known we will use t statistics

P value is TDIST(3.16,9,2)=0.0116<alpha=0.05

As P value is less than alpha we reject the null hypothesis

Hence we have sufficient evidence that mean is different from 2500