The maintenance department in charge of a city's street lights finds that it is cost-efficient to replace all street light bulbs at once (1 bulb per streetlight), rather than replace bulbs...

Extracted text: The maintenance department in charge of a city's street lights finds that it is cost-efficient to replace all street light bulbs at once (1 bulb per streetlight), rather than replace bulbs individually as they burn out. Assume the lifetime of a bulb is normally distributed with a mean of 3000 hours and a standard deviation of 200 hours. The department wants, on average, no more than 2.5% of the bulbs to burn out before replacement. With reference to the information, another stretch of road has 73 streetlights. What are the mean and standard deviation of the number of bulbs that will already be burned out on this stretch of road at the scheduled replacement time?