Exponential Distribution problem

I am having trouble undestanding this question:

The daily failure rate of an electrical component follows an exponential distribution with mu=0.72. What is the chance of a randomly selected component failing between 22 hours and 56 hours.

Do I have to covert the hours into days? When I work it out the formula P(x)= 1-e^-(mu)(x) with P(22) and P(56) I get both answers close to 1. So does that mean there is a 100% chance that it will fail or a 0% chance that it will fail?

Help!! :eek: