First let's convert the minutes to hours (multiply minutes by 60 to get hours):
30 × 60 = 1,800 drops/hour
Now that you know how much drops there are per hour, you can multiply this answer by 3 to work out how many drops there are in 3 hours:
1,800 × 3 = 5,400 drops
We know that 5 drops is equal to 1 ml, so we can divide 5,400 by 5 to work out the amount of ml:
5,400 ÷ 5 = 1,080 ml
Therefore, your final answer is 1,080 millilitres (ml)
