Finding the Fourth Proportional to 1,145.59, 1,580.87 and 621.61

Step by Step Solution

1. Step 1: Write the proportion equation
   1,145.59 : 1,580.87 = 621.61 : x
2. Step 2: Convert to fraction form
   1,145.59/1,580.87 = 621.61/x
3. Step 3: Cross multiply
   1,145.59x = 1,580.87 × 621.61
4. Step 4: Simplify right side
   1,145.59x = 982,673.59
5. Step 5: Solve for x
   x = 982,673.59/1,145.59
6. Step 6: Final answer
   x = 857.79