Company XYZ know that replacement times for the quartz time pieces it produces are normally distributed with a mean of 16.4 years and a standard deviation of 1.3 years.

If the company wants to provide a warranty so that only 0.5% of the quartz time pieces will be replaced before the warranty expires, what is the time length of the warranty?

warranty =years

Enter your answer as a number accurate to 1 decimal place. Answers obtained using exactz-scores orz-scores rounded to 3 decimal places are accepted.