Finding the Fourth Proportional to 1,087.61, 1,500.89 and 621.86

Step by Step Solution

1. Step 1: Write the proportion equation
   1,087.61 : 1,500.89 = 621.86 : x
2. Step 2: Convert to fraction form
   1,087.61/1,500.89 = 621.86/x
3. Step 3: Cross multiply
   1,087.61x = 1,500.89 × 621.86
4. Step 4: Simplify right side
   1,087.61x = 933,332.84
5. Step 5: Solve for x
   x = 933,332.84/1,087.61
6. Step 6: Final answer
   x = 858.15