If a seismic station is 3200 km from an earthquake epicenter, what is the time needed for an S-wave to travel from the epicenter to the seismic station

Toward the end of the roman empire, what caused a decrease in the use of coined money tell me now

How has the money from oil production in the middle east not impacted the people of that region? a) it improved education and jobs in the region. b) it improved infrastructure such as ports, roads, and bridges. c) it increased life expectancy due to improved healthcare facilities. d) it increased political stability and lessened the presence of corruption.

Which answer best describes the main purpose of the monroe doctrine? a to establish fixed borders in the western territories b to keep europe from further colonizing the western hemisphere c to limit the ability of the free states to protect runaway slaves d to promote settlement of the louisiana purchase