Finding the Fourth Proportional to 643,789,061.12, 965,683,902.72 and 212,967,557.12

Step by Step Solution

1. Step 1: Write the proportion equation
   643,789,061.12 : 965,683,902.72 = 212,967,557.12 : x
2. Step 2: Convert to fraction form
   643,789,061.12/965,683,902.72 = 212,967,557.12/x
3. Step 3: Cross multiply
   643,789,061.12x = 965,683,902.72 × 212,967,557.12
4. Step 4: Simplify right side
   643,789,061.12x = 205,659,341,712,386,144
5. Step 5: Solve for x
   x = 205,659,341,712,386,144/643,789,061.12
6. Step 6: Final answer
   x = 319,451,438.57