posted by Maria .
If the life in years, of a television set is normally distributed with a mean of 46 years and a standard deviation of 4 years, what should be the guarantee period if the company wants less than 3% of the television sets to fail while under warranty?
That would be about two sigma less than the mean, but did you really mean 46 years mean life? No one keeps a TV set that long, nor is there accurate lifetime data available.
I know but that's what the question asked.
In that case, 97% will last longer than 38 years.