Please use software for avoiding rounding error.

In a grocery store, there is one cashier counter. Customers arrive at the cashier counter according to a Poisson process. The arrival rate is 25 customers per hour. The service time is exponentially distributed. The mean service time is 1 minute 30 seconds.

What is the expected number of customers waiting in the system (L)? Only number will be accepted for the answer and write up to two digits after the decimal point if you need.