CREATE TABLE table_6461 ("District" CLOB, "2010 Population  ( 000 ) " FLOAT, "2008 GDP  ( USD bn )  a" FLOAT, "2008 GDP per capita  ( USD )  a" FLOAT, "Agri culture b" FLOAT, "Mining b" FLOAT, "Manufac turing b" FLOAT, "Services & cons truction b" FLOAT, "Exports  ( USD mn )  2011" CLOB, "Median mo. salary  ( USD )  a e" FLOAT, "Vehicles  ( per 1000 )  d" FLOAT, "Income poverty f" FLOAT, "Structural poverty g" FLOAT)

Manufac turing b of 16.8, and a 2008 GDP per capita (USD) a smaller than 4,162, so what is the total number of mining b?
SELECT COUNT("Mining b") FROM table_6461 WHERE "Manufac turing b" = '16.8' AND "2008 GDP per capita (USD) a" < '4,162'
SELECT COUNT("Mining b") FROM "table_6461" WHERE "2008 GDP per capita (USD) a" < '4,162' AND "Manufac turing b" = '16.8'