Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

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

### Question ###
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?

### Accurate SQL ###

SELECT COUNT("Mining b") FROM table_6461 WHERE "Manufac turing b" = '16.8' AND "2008 GDP per capita (USD) a" < '4,162'