A marketing group is studying population trends. It predicts that the population P of a certain city will increase at the rate of dP/dt people per year, where dP/dt=15000/sqrt____ and t is the number of years past 1980. What is the expected increase in population from 1980 to 2001?
举一反三
- The author of the passage intends to _________. A: warn people against the population explosion in the near future B: compare the demographic growth pattern in the past with that after 1650 C: find out the cause for rapid increase in population in recent years D: present us a clear and complete picture of the demographic growth
- A country's urbanization can be seen from its increase in______. A: wealth B: population C: the number of cities D: urban areas
- ___________________ refers to a rapid increase in the size of a population caused by such factors as a sudden decline in infant mortality or an increase in life expectancy. It particularly means the very great and continuing increase in human population in modern times. Optimal population size appears adequate for economy, education, healthcare, and environment.
- The influence of weights on the weighted arithmetic mean is determined by () A: Value size of each group of character values B: What is the absolute number of weights C: Proportion of the number of units in each group to the population number of units D: What is the population number of units
- Age distribution is the number of individuals of each age in the population which influences greatly the rate of population growth。 （ ）