Finding the Fourth Proportional to 1,561.89, 2,155.10 and 898.77

Step by Step Solution

1. Step 1: Write the proportion equation
   1,561.89 : 2,155.10 = 898.77 : x
2. Step 2: Convert to fraction form
   1,561.89/2,155.10 = 898.77/x
3. Step 3: Cross multiply
   1,561.89x = 2,155.10 × 898.77
4. Step 4: Simplify right side
   1,561.89x = 1,936,934.73
5. Step 5: Solve for x
   x = 1,936,934.73/1,561.89
6. Step 6: Final answer
   x = 1,240.12