Answer:
3.0 g/mL
Explanation:
The volume is the difference in water levels:
17.5 mL -15.0 mL = 2.5 mL
The density is the ratio of mass to volume:
(7.50 g)/(2.5 mL) = 3.0 g/mL
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Taking the difference of "large" numbers reduces the number of significant figures to 2, so that is the number the answer must use. All other numbers here have 3 significant digits.
