Answer: 0.06 litre or 60 ml
Explanation:
Given: The capacity of glass tank= 26 liter
If he add 20.9 liters of water after 85 marbles to fill it completely, then
The volume of 85 marbles=
![26-20.9=5.1\ liters](https://img.qammunity.org/2020/formulas/mathematics/middle-school/dvbm1m1aou7lu5toho1xhkzugtah7skqs4.png)
Since, the marbles have same volume.
∴ Volume of each marble=
![\frac{\text{volume of 85 marbles}}{\text{85}}](https://img.qammunity.org/2020/formulas/mathematics/middle-school/5yfln7t0huxa21qi4n4e73jnko6y1wl7pr.png)
⇒ Volume of each marble=
![(5.1\ litre)/(85)=0.06\ liters](https://img.qammunity.org/2020/formulas/mathematics/middle-school/qpyew2lm77y7re2f5fit53wnzqxscrg5tz.png)
In milliliters, Volume of each marble=
![0.06*1000=60ml](https://img.qammunity.org/2020/formulas/mathematics/middle-school/fgr92pnwlhj8f1qagl93pitn4i1emyk55d.png)