Finding the Fourth Proportional to 1,145.31, 1,580.53 and 621.34

Step by Step Solution

1. Step 1: Write the proportion equation
   1,145.31 : 1,580.53 = 621.34 : x
2. Step 2: Convert to fraction form
   1,145.31/1,580.53 = 621.34/x
3. Step 3: Cross multiply
   1,145.31x = 1,580.53 × 621.34
4. Step 4: Simplify right side
   1,145.31x = 982,046.51
5. Step 5: Solve for x
   x = 982,046.51/1,145.31
6. Step 6: Final answer
   x = 857.45