Finding the Fourth Proportional to 1,189,518.72, 1,641,499.20 and 645,628.80

Step by Step Solution

1. Step 1: Write the proportion equation
   1,189,518.72 : 1,641,499.20 = 645,628.80 : x
2. Step 2: Convert to fraction form
   1,189,518.72/1,641,499.20 = 645,628.80/x
3. Step 3: Cross multiply
   1,189,518.72x = 1,641,499.20 × 645,628.80
4. Step 4: Simplify right side
   1,189,518.72x = 1,059,799,158,696.96
5. Step 5: Solve for x
   x = 1,059,799,158,696.96/1,189,518.72
6. Step 6: Final answer
   x = 890,947.86