Below is an instruction that describes a task. Write a response that appropriately completes the request.

### Instruction:
What is the CHI (Carvill Hurricane Index) when the NHC advisory number is equal to 49b?

### Inputs:
table_name: table, columns: ['Name', 'Year', 'Landfall', 'NHC Advisory Number', 'V(mph)', 'R(miles)', 'Saffir-Simpson Category', 'CHI']

### Response:
SELECT CHI FROM table WHERE NHC Advisory Number = 49B