solve using given info

The lifespan of a certain brand of an electric motor is normally distributed with a mean value of 10 with a standard deviation of 2 years. Find the 90% percentile of the motor lifespans, i.e., find a value c so that there is an 90% chance that a randomly selected motor's lifespan is less than c, and there is a 10% chance that a motor's lifespan exceeds c. 2.56 11.68 13.85 12.56 13.79