Amelia needs to estimate the quantity , where , , and are large positive integers. She rounds each of the integers so that the calculation will be easier to do mentally. In which of these situations will her answer necessarily be greater than the exact value of ?
She rounds all three numbers up.
She rounds and up, and she rounds down.
She rounds and up, and she rounds down.
She rounds up, and she rounds and down.
She rounds up, and she rounds and down.
