To find the approximate weight of the water in an Olympic-sized swimming pool, we can multiply the number of gallons by the weight of one gallon of water.
The pool holds \( 6.6 \times 10^5 \) gallons, and each gallon weighs about 8.3 pounds.
Now we calculate the total weight:
\[ \text{Total Weight} = 6.6 \times 10^5 , \text{gallons} \times 8.3 , \text{lb/gallon} \]
Now we can perform the multiplication:
\[ 6.6 \times 8.3 = 54.78 \]
Next, we multiply the powers of ten:
\[ 10^5 \]
Putting it all together, we get:
\[ \text{Total Weight} = 54.78 \times 10^5 , \text{lb} \]
To write this in proper scientific notation, we can convert \( 54.78 \) into \( 5.478 \) and increase the power of ten by 1:
\[ 54.78 \times 10^5 = 5.478 \times 10^6 \]
So, the approximate weight of the water in an Olympic-sized swimming pool is:
\[ \boxed{5.478 \times 10^6 , \text{lb}} \]