Question

A brain weighing 1.00 lbs occupies a volume of 620 mL. What is the specific gravity of the brain?

Answer 1

1 lb = 454 grams (approximately). You can look it up if you want more accuracy (for example 453.59 g).

$density = \frac{mass}{volume} \\ =\frac{454g}{620mL}=0.73 g/mL$