1) A manufacturer produces bearings, but because of variability in the production process, not all of the bearings have the same diameter. The diameters have a normal distribution with a mean of1.7centimeters (cm) and a standard deviation of0.02cm.The manufacturer has determined that diameters in the range of1.68to1.72cm are acceptable. What proportion of all bearings falls in the acceptable range? (Round your answer to four decimal places.)

2)A large manufacturing plant uses lightbulbs with lifetimes that are normally distributed with a mean of1100hours and a standard deviation of60hours. To minimize the number of bulbs that burn out during operating hours, all bulbs are replaced at once. How often should the bulbs be replaced so that no more than 1% burn out between replacement periods? (Round your answer to one decimal place.)

3)A company that produces an expensive stereo component is considering offering a warranty on the component. Suppose the population of lifetimes of the components is a normal distribution with a mean of89months and a standard deviation of8months. If the company wants no more than 2% of the components to wear out before they reach the warranty date, what number of months should be used for the warranty? (Enter your answer as a whole number.)