Assume the lifetimes of a certain light bulb are normally distributed with a mean of 10 months and a standard deviation of 2 months. What is the probability that the lifetime of a given light bulb is...

Assume the lifetimes of a certain light bulb are normally distributed with a mean of 10 months and a standard deviation of 2 months. What is the probability that the lifetime of a given light bulb is between 6 and 9 months? 0.2857 Answer is not given in the choices. 0.0548 0.0190 0.7882