Finding the Fourth Proportional to 1,145.40, 1,580.61 and 621.42

Step by Step Solution

1. Step 1: Write the proportion equation
   1,145.40 : 1,580.61 = 621.42 : x
2. Step 2: Convert to fraction form
   1,145.40/1,580.61 = 621.42/x
3. Step 3: Cross multiply
   1,145.40x = 1,580.61 × 621.42
4. Step 4: Simplify right side
   1,145.40x = 982,219.56
5. Step 5: Solve for x
   x = 982,219.56/1,145.40
6. Step 6: Final answer
   x = 857.53