Finding the Third Proportional to 257,706 and 390,123.75

Step by Step Solution

1. Step 1: Write the proportion equation
   257,706 : 390,123.75 = 390,123.75 : x
2. Step 2: Convert to fraction form
   257,706/390,123.75 = 390,123.75/x
3. Step 3: Cross multiply
   257,706x = 390,123.75 × 390,123.75
4. Step 4: Simplify right side
   257,706x = 152,196,540,314.06
5. Step 5: Solve for x
   x = 152,196,540,314.06/257,706
6. Step 6: Final answer
   x = 590,582.06