Finding the Third Proportional to 128,865,831,118 and 261,406,111,740

Step by Step Solution

1. Step 1: Write the proportion equation
   128,865,831,118 : 261,406,111,740 = 261,406,111,740 : x
2. Step 2: Convert to fraction form
   128,865,831,118/261,406,111,740 = 261,406,111,740/x
3. Step 3: Cross multiply
   128,865,831,118x = 261,406,111,740 × 261,406,111,740
4. Step 4: Simplify right side
   128,865,831,118x = 68,333,155,255,025,364,107,264
5. Step 5: Solve for x
   x = 68,333,155,255,025,364,107,264/128,865,831,118
6. Step 6: Final answer
   x = 530,265,894,862.81