National Welding Company Uses Industrial Robots in Some of Its

Multiple Choice

National Welding Company uses industrial robots in some of its assembly-line operations. Management has determined that the lengths of time in hours between breakdowns are exponentially distributed with probability density function . ​
What is the probability that a robot selected at random will break down between 400 and 500 hr of use? Round your answer to the nearest hundredth.
​

A) 0.06
B) ​0.30
C) ​0.15
D) ​0.79
E) ​0.51