The quality-control manager at a light emitting diode (LED) factory needs to determine whether the mean life of a large shipment of LEDs is equal to 50,000 hours. The population standard deviation is 1,500 hours. A random sample of 64 LEDs indicates a sample mean life of 49,875 hours.

At the 0.05 level of significance, is there evidence that the mean life is different from 50,000 hours?

Compute the p-value and interpret its meaning.

Construct a 95% confidence interval estimate of the population mean life of the LEDs.

Compare the results of (a) and (c). What conclusions do you reach?