Finding the Third Proportional to 128,389.50 and 278,460

Step by Step Solution

1. Step 1: Write the proportion equation
   128,389.50 : 278,460 = 278,460 : x
2. Step 2: Convert to fraction form
   128,389.50/278,460 = 278,460/x
3. Step 3: Cross multiply
   128,389.50x = 278,460 × 278,460
4. Step 4: Simplify right side
   128,389.50x = 77,539,971,600
5. Step 5: Solve for x
   x = 77,539,971,600/128,389.50
6. Step 6: Final answer
   x = 603,943.25