Statistical question about number of failures?

I think the problem asks for the expected total number of failures of pumps over a period of 100hours. Since the MTTF of each pump is 100 hours, it can be concluded that the expected number of failures for each pump per 100 hours is 1. In other words, the number of failures of each pump follows a Poisson distribution with λ=1 if the time period is 100hours. Since pumps work and fail independently, the total number of failures of 100 pumps working a period of 100 hours will follow a Poisson distribution with λ=100. This means the expected total number of failures of 100 pumps over a period of 100hours is 100.