How can scientists use a seismograph to determine earths density?

Arid and semiarid subcategories are part of which climate

Reading graphs: unemployment us unemployment rate (1961-2011) identify the trends in the graph and then use the drop- down menu to complete each statement from 1961 to 1965 unemployment was in the mid-2000s through 2011. unemployment was percentage unemployed 1961 1971 1981 1991 2001 2011 year

South america is located within which hemisphere?