Question

a graduated cylinder has a mass of 50 g when empty. when 30 ml of oil is added, the graduated cylinder and oil now has a mass of 74 g. if a rock is added to the graduated cylinder, the oil level rises to 80 ml and the total mass is now 250g.
what is the density of the rock?
what is the density of the oil?

Explanation:

Step1: Find mass of oil

Mass of oil = 74 g - 50 g = 24 g

Step2: Find volume of oil

Volume of oil = 30 mL

Step3: Calculate oil density

Density of oil = $\frac{24\ g}{30\ mL}$ = 0.8 g/mL

Step4: Find volume of rock

Volume of rock = 80 mL - 30 mL = 50 mL

Step5: Find mass of rock

Mass of rock = 250 g - 74 g = 176 g

Step6: Calculate rock density

Density of rock = $\frac{176\ g}{50\ mL}$ = 3.52 g/mL

Answer:

Density of oil: 0.8 g/mL, Density of rock: 3.52 g/mL