1) If light bulbs have lives that are normally distributed with a mean of 2500 hours and a standard deviation of 500 hours what percentage of light bulbs have a life less than 2500 hours?2)The lifetimes of light bulbs of a particular type are normally distributed with a mean of 370 hours and a standard deviation of 5 hours. What percentage of bulbs has lifetimes that lie within 1 standard deviation of the mean on either side3) The amount of Jen s monthly phone bill is normally distributed with a mean of $60 and a standard deviation of $12. Fill in the blanks:68% of her phone bills are between $______________ and $______________.4)The amount of Jen s monthly phone bill is normally distributed with a mean of $50 and a standard deviation of $10. Find the 25th percentile.5) The diameters of bolts produced by a certain machine are normally distributed with a mean of 0.30 inches and a standard deviation of 0.01 inches. What percentage of bolts will have a diameter greater than 0.32 inches?6)The annual precipitation amounts in a certain mountain range are normally distributed with a mean of 88 inches and a standard deviation of 10 inches. What is the likelihood that the mean annual precipitation during 25 randomly picked years will be less than 90.8 inches? 7) A final exam in Statistics has a mean of 73 with a standard deviation of 7.73. Assume that a random sample of 24 students is selected and the mean test score of the sample is computed. What percentage of sample means are less than 708) A mean score on a standardized test is 50 with a standard deviation of 10. Answer the following1. What scores fall between 1 and +1 standard deviation?2. What percent of all scores fall between 1 and +1 standard deviation?3. What score falls at +2 standard deviations?4. What percentage of scores falls between +1 and +2 standard deviations?
