The lifespan of a light bulb manufactured by a certain company is measured by random variable X with the following probability density function:
f(x) =
0.04e^(-0.04x) if x > 0
0 otherwise
where x denotes the life, in hours, of a randomly chosen bulb.
What is the probability that the lifespan of the bulb is between 50 and 70 hours? (Round your answer to 4 decimal places)