1. The manager at a lightbulb factory wants to determine whether there is any di

Question

1. The manager at a lightbulb factory wants to determine whether there is any difference in the mean life expectancy of bulbs manufactured on two different types of machine. A random sample of 30 lightbulbs from machine I indicates a sample mean of 375 hours and a sample standard deviation of 100 hours. A sample of 30 from machine II indicates a sample mean of 352 hours and a sample standard deviation of 115 hours. At a 5% level of significance, is there evidence of a difference in the mean life of lightbulbs produced by the two types of machine?

Explanation / Answer

Ho: 1=2

Ha:1 =/ 2

t= (375-352)/(100^2/30 +115^2/30)= 0.826

At degrees of freedom 30-1=29 p>.40 (which is much greater than .05) so there is no evidence of a difference between mean lives of the lightbulbs.

Related Questions

Navigate

• Browse (All)
• Browse 1
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.