The lengths of time (in hours) an incandescent light bulb can stay lit solidly are normally distributed, with a mean of 62 hours and a standard...

The lengths of time (in hours) an incandescent light bulb can stay lit solidly are normally distributed, with a mean of 62 hours and a standard deviation of 4.4 hours.  Use this information to answer questions #16-20.

1. What percent of light bulbs can last within one standard deviation of the mean, between 57.6 hours and 66.4 hours?
2. A company considers a bulb defective if it can only last 50 hours straight.  What portion of light bulbs would this company consider defective?
3. An energy-efficient bulb can stay lit for at least 68 hours.  What percent of incandescent bulbs can stay lit for that long?
4. What portion of light bulbs can stay lit for between 55 and 65 hours straight?
5. The top 2% of light bulbs can stay lit for at least how long?