Question

The life in hours of a 75-watt light bulb is known to be approximately normally distributed, with standard deviation σ = 25 hours. A random sample of 62 bulbs has a mean life of x-bar = 1,014 hours. Construct a 98% confidence interval around the true population mean life of the light bulb.

Answer 1

Solution:-

98% confidence interval around the true population mean life of the light bulb is C.I = ( 1006.61, 1021.39).

n = 62, Mean = 1014, σ = 25

C.I = 1014 + 2.327*3.1750032

C.I = 1014 + 7.3882

C.I = ( 1006.61, 1021.39)