Finding the Third Proportional to 128,865,831,109 and 261,406,111,721

Step by Step Solution

1. Step 1: Write the proportion equation
   128,865,831,109 : 261,406,111,721 = 261,406,111,721 : x
2. Step 2: Convert to fraction form
   128,865,831,109/261,406,111,721 = 261,406,111,721/x
3. Step 3: Cross multiply
   128,865,831,109x = 261,406,111,721 × 261,406,111,721
4. Step 4: Simplify right side
   128,865,831,109x = 68,333,155,245,091,935,223,808
5. Step 5: Solve for x
   x = 68,333,155,245,091,935,223,808/128,865,831,109
6. Step 6: Final answer
   x = 530,265,894,822.76