سؤال قراءة ستيب محلول — فهم التفاصيل (تدريب 5955)

(1) The life expectancy is the average age to which a newborn baby can be expected to live. In Europe between 1830 and 1900 the life expectancy was 40-50 years. Between 1900 and 1950 it rose to 65 and now it is 73-74 years. In central Africa, life expectancy was rising to 58 years until the AIDS epidemic caused it to fall back to about 45 years. (2) These figures are averages. They do not mean, for example, that everyone in the developing world will live to the age of 58. In the developing world, 40% of the deaths are of children younger than 5 years and only 25 - 30% are deaths of people over 60. In Europe’s, only 5 - 20% of deaths are those of children below the age of 5, but 70-80% are of people over 60. (3) An increase in the number of people over the age of 60 does not change the rate of population growth much, because these people are past the age when they can have children. On the other hand, if the death rate among children falls and the extra children survive to have children of their own, then the population will continue to grow. This is the chief reason for the rapid population growth in the developing world since 1950