user: Question: if the estimated exposure ( mrem )/hr* is 0.28, what is the specimen weight/size?
Columns: ['Specimen weight/size', 'Calculated activity ( Bq )', 'Calculated activity ( Ci )', 'Estimated activity GR(api)', 'Estimated exposure ( mRem )/hr*']
Types: ['text', 'real', 'text', 'text', 'text']
Sample row: ['1000 g / 8.79 cm', 183355.0, '4.96×10 −6', '8,449.31', '2.78']
SQL:

assistant: SELECT "Specimen weight/size" FROM "Table" WHERE "Estimated exposure ( mRem )/hr*" = '0.28';