Question

Alex filled a 5 gallon jug with water. How many litres of water are in the container? \[\]

Answer 1

Hint: We recall the definition of litre and gallon as measurement units for liquid. We convert from gallons to litre using the conversion that 1 gallon is equal to $\text{3}.\text{785}~$ litre. We multiply 5 using decimal multiplication methods to find the result. \[\]

Complete step by step answer:
We know that litres are units of fluid capacity and volume. The amount of liquid with unit density contained in the space by a cube of side of 1 cm is called 1 millilitre (ml). So the 1ml liquid is contained in $1cm\times 1cm\times 1cm=1c{{m}^{3}}$ of space. We also know that 1 litre is 1000 ml. \[\]
We know that gallon is also a unit to measure fluid capacity and volume. 1 gallon in the United States is equivalent to the amount of liquid that can be contained by a cube of 231 inches. The conversion from gallon to litre is
\[\text{1 gallon }=\text{ 3}.\text{785}~\text{ litre}\]
 We are given the question that Alex filled a 5 gallon jug with water and are asked how many litres of water in the jug. So the jug 5 times one gallon that is 5 times $3.875$ litre which is
\[5\times 3.785\]
We know how to multiply with decimal. We multiply forgetting the decimal point as to have $5\times 3875=18925$. We then count the total number of non-zero digits after the decimal point in the multiplying number which here is 3. So we put the decimal point 3 digits from the right to have
\[5\times 3.785\text{ litre}=18.925\text{ litre}\]

Note:
We note that exact conversion from gallon to litre is $\text{1 gallon }=\text{ 3}.\text{785}~411784\text{ litre}$. We can convert according to our required approximation. We also note that 1 imperial gallon is $4.546$ litre and 1 dry US gallon is $4.405$ litre. The gallon unit is primarily used to measure crude oil like petrol. The symbol for gallon is $gal$.