单项选择题

People tend to underestimate their life expectancy, and it’s not surprising. It’s the look around problem again: You generalize from life spans of older friends and family members and figures that’s what’s in store for you, too. But in an era of rapidly improving life expectancy, the look-around method once again gives the wrong answer.
Life expectancy at age 65 today is 15.6 additional years for woman. For both sexes, this represents an increase of more than two years just since 1970. By the time the youngest baby boomers turn 65, the Social Security Administration projects that life expectancy at that age could be as high as 18 more years for men and 21 years for women. Note that everyone runs very nearly a 50 percent "risk" of living longer than their life expectancy.
That reality makes retirement planning exceptionally difficult. On the day a husband and wife turn 65, they may have only a year or two of living between them to finance, or they may have 70. A good rule of thumb(单凭经验来做的方法) might be to plan against the possibility that you will outlive three quarters of the people in your age group — an actuarial(保险核计的) calculation our Web site calculator allows you to make. You may not want to deny a child a college education just so you are sure to have enough money to celebrate your 95th birthday, but you also don’ t want to become a burden on your children just because you unexpectedly live to be 10 years older than the average life expectancy for people of your age.

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