Let the Lifetime of a New Jet Ski Be Represented

Multiple Choice

Let the lifetime of a new Jet Ski be represented by a lognormal variable, Y = e^X where X is normally distributed. Let the mean of the lifetime of the Jet Ski be six years with a standard deviation of three years. What proportion of the Jet Skis will last less than seven years?

A) 0.2877
B) 0.3707
C) 0.6293
D) 0.7131