Question

1. A random sample of 56 fluorescent light bulbs has a mean life of 645 hours. As- sume the population standard deviation is 31 hours. a) Construct a 95% confidence interval for the population mean. b) If one of the light bulbs only lasted 620 hours, would that be unusual? c) If the population mean of the all of the light bulbs turned out to be 620 hours, would you be surprised?

Answer 1

645A 31 0. oS 56 1. ** Ak) o.02 96 636.88, 653 u the interal (636.38, 653.12 mean net 6 20 krs, it w be unurual ulbs fron 94 ene bulb Last onty as ther can e deviatins in the calculat 2. fee a =620 hr, that would be fhe nean epect, 1/ 6 tae times, mapiong peply as the cenficlence fnterwal within e an