Question

1. A computer information systems manager was in charge of purchasing new battery packs for laptop computers. The choices were narrowed to two available models. Since the two models cost about the same, the manager was interested in determining whether there was a difference in the average time the battery packs would function before needing to be recharged. Based on two independent random samples, the following summary information was computed:

	Battery Pack Model 1	Battery Pack Model 2
Sample Size	30	30
Sample Mean	6 hours	6.5 hours
Standard Deviation	1.8 hours	2.6 hours

1. Find a 95% confidence interval for the difference in average functioning time before recharging in the two models (z-value= 1.96).
2. Based on the interval in the previous question, can one conclude there is a difference in the true average functioning time before recharging between the two models of battery packs? Justify your answer.

Answer 1