Question

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?
drwls
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.
Maria
I know but that's what the question asked.
Thanks
drwls
In that case, 97% will last longer than 38 years.