Answer:
24
they each will need to fill their bottle 24 times (48 times in total)
Explanation:
There are 768 ounces in 6 gallons.
If each bottle carries 16 ounces in total to fill up the tank it would take 48 bottles. ( 48*16=768)
There is two students though, so you split it. (48/2=24)
Therefore each student need to fill there bottle 24 times to fill up the tank.