user: Question: What is the CHI (Carvill Hurricane Index) when the NHC advisory number is equal to 49B?
Columns: ['Name', 'Year', 'Landfall', 'NHC Advisory Number', 'V(mph)', 'R(miles)', 'Saffir-Simpson Category', 'CHI']
Types: ['text', 'real', 'text', 'text', 'real', 'real', 'real', 'text']
Sample row: ['Bonnie', 1998.0, 'North Carolina', '31B', 115.0, 115.0, 3.0, '10.7']
SQL:

assistant: SELECT "CHI" FROM "Table" WHERE "NHC Advisory Number" = '49B';