Finding the Third Proportional to 261,276.50 and 390,899

Step by Step Solution

1. Step 1: Write the proportion equation
   261,276.50 : 390,899 = 390,899 : x
2. Step 2: Convert to fraction form
   261,276.50/390,899 = 390,899/x
3. Step 3: Cross multiply
   261,276.50x = 390,899 × 390,899
4. Step 4: Simplify right side
   261,276.50x = 152,802,028,201
5. Step 5: Solve for x
   x = 152,802,028,201/261,276.50
6. Step 6: Final answer
   x = 584,828.82