The lifetime of 100-watt light bulbs is normally distributed with a mean of 750 hours and a standard deviation of 20 hours. Owing to strict quality control during the manufacturing process, 95% of the bulbs will last at least 717.1 hours, while 75% of the bulbs will last at most 763.5 hours. If a 100-watt bulb is selected at random, what will be its expected lifetime (in hours)?