6. A comparison of life expectancy in random samples of 40 less-developed countries and 31 industrialized countries reveals the following (fictional) data. The standard deviations are significantly different from one another. Is there a significant difference in mean life expectancy between countries with these two levels of economic development? X=life expectancy of the resident at birth. Less-Developed Countries Mean=66.1 years N=40 Standard error of the difference between means=.60 Industrialized Countries Mean=76.7 years N=31

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