8) The population of a town in three consecutive years are 5000, 7000 and 8400 respectively. The population of the town in the fourth consecutive year according to geometrical increase method is

9) The suitable method of forecasting popu¬lation for a young and rapidly increasing city is

10) , The depression of water table in a well due to pumping will be maximum[where R is the radius of influence]

11) The devices which are installed for drawing water from the sources are called

12) Select the correct relationship between porosity (N), specific yield (y) and specific retention (R)