CREATE TABLE table_39416 ("Call sign" TEXT, "Frequency MHz" FLOAT, "City of license" TEXT, "ERP W" FLOAT, "Class" TEXT, "FCC info" TEXT)

What is the average frequency in MHz for stations with an ERP W of 170?
SELECT AVG("Frequency MHz") FROM table_39416 WHERE "ERP W" = '170'
SELECT AVG("Frequency MHz") FROM "table_39416" WHERE "ERP W" = '170'