Finding the Fourth Proportional to 1,187,124.78, 1,638,237.89 and 643,261.57

Step by Step Solution

1. Step 1: Write the proportion equation
   1,187,124.78 : 1,638,237.89 = 643,261.57 : x
2. Step 2: Convert to fraction form
   1,187,124.78/1,638,237.89 = 643,261.57/x
3. Step 3: Cross multiply
   1,187,124.78x = 1,638,237.89 × 643,261.57
4. Step 4: Simplify right side
   1,187,124.78x = 1,053,815,474,667.45
5. Step 5: Solve for x
   x = 1,053,815,474,667.45/1,187,124.78
6. Step 6: Final answer
   x = 887,704.05