Light Bulbs Are Normally Distributed with an Average Lifetime of 1000

question 108

Multiple Choice

Light bulbs are normally distributed with an average lifetime of 1000 hours and a standard deviation of 250 hours. The probability that a light bulb picked at random will last less than 1500 hours is about:

• A)97.72 percent.
• B)95.44 percent.
• C)75.00 percent.
• D)68.00 percent.