Finding the Third Proportional to 290,090 and 443,721

Step by Step Solution

1. Step 1: Write the proportion equation
   290,090 : 443,721 = 443,721 : x
2. Step 2: Convert to fraction form
   290,090/443,721 = 443,721/x
3. Step 3: Cross multiply
   290,090x = 443,721 × 443,721
4. Step 4: Simplify right side
   290,090x = 196,888,325,841
5. Step 5: Solve for x
   x = 196,888,325,841/290,090
6. Step 6: Final answer
   x = 678,714.63