There is the apparent paradox ( ) the effective cause of the high proportion of the old is births rather than deaths.

One major obstacle to economic development is population growth. The populations of most developing countries grow at a rate much faster than that of in dustrialized countries. One reason for this growth is the high crude birth-rate—the number of live births per 1,000 people.（） A: to B: The populations C: that D: live births

There has been a great __________ in the number of births in these parts five years. A: advancement B: skip C: aise D: leap

The<br/>birth _____ is the number of births compared to the number of the<br/>people. () A: speed B: rate C: frequency D: percentage

Nowadays the number of births, like the age of death, has become [u]average[/u].  A: 平均数 B: 通常的 C: 平均为 D: 正常标准

Infant _________rate is the number of infants dying before reaching one year of age, per 1,000 live births in a given year. A: mortality B: incidence C: disability D: survival

Spinal muscular atrophy (SMA)is diagnosed in approximately one out of every _________ live births and is the leading genetic cause of infant mortality. A: 8,000 B: 10,000 C: 12,000 D: 15,000

If a population of 100,000 have 2,000 births, 500 deaths, 100 immigrants, and 200 emigrants in one year, what is the growth rate? A: 2.0% B: 1.7% C: 1.6% D: 1.4% E: 0.4%

Suppose that in the year 2015 the number of births is temporarily high. How does this baby boom affect the price of babysitting services in 2020 and 2030?(Hint:5-year-olds need babysitters,whereas 15-year-olds can be babysitters.)

For a certain group of births, the number (y) of people that survive to age x years is given by y=2400*sqrt(196-2x). Find the rate of change of y with respect to x when x = 26. A: none of the above B: 200 C: -200 D: -100 E: 100