Finding the Fourth Proportional to 1,145.55, 1,580.82 and 621.57

Step by Step Solution

1. Step 1: Write the proportion equation
   1,145.55 : 1,580.82 = 621.57 : x
2. Step 2: Convert to fraction form
   1,145.55/1,580.82 = 621.57/x
3. Step 3: Cross multiply
   1,145.55x = 1,580.82 × 621.57
4. Step 4: Simplify right side
   1,145.55x = 982,590.29
5. Step 5: Solve for x
   x = 982,590.29/1,145.55
6. Step 6: Final answer
   x = 857.75