Finding the Third Proportional to 128,865,831,123 and 261,406,111,749

Step by Step Solution

1. Step 1: Write the proportion equation
   128,865,831,123 : 261,406,111,749 = 261,406,111,749 : x
2. Step 2: Convert to fraction form
   128,865,831,123/261,406,111,749 = 261,406,111,749/x
3. Step 3: Cross multiply
   128,865,831,123x = 261,406,111,749 × 261,406,111,749
4. Step 4: Simplify right side
   128,865,831,123x = 68,333,155,259,730,676,940,800
5. Step 5: Solve for x
   x = 68,333,155,259,730,676,940,800/128,865,831,123
6. Step 6: Final answer
   x = 530,265,894,878.74