<PRE><B>Question 316598</B>
The XYZ Company tested a new product and found its lifetime to be normally distributed, with a mean life of 146 days and a standard deviation of 19.5 days. what is the probability that a product will last between 154 and 180 days? 
--------------
Find the z-values:
z(154) = (154-146)/19.5 = 0.4103
 ---
z(180) = (180-146)/19.5 = 1.7436
-------------------------------------
P(154 &lt; x &lt;  180) = P(0.4103 &lt; z &lt; 1.7436) = 0.3002
=======================================================
Cheers,
Stan H.</PRE>