Finding the Fourth Proportional to 1,145.39, 1,580.64 and 621.42

Step by Step Solution

1. Step 1: Write the proportion equation
   1,145.39 : 1,580.64 = 621.42 : x
2. Step 2: Convert to fraction form
   1,145.39/1,580.64 = 621.42/x
3. Step 3: Cross multiply
   1,145.39x = 1,580.64 × 621.42
4. Step 4: Simplify right side
   1,145.39x = 982,243.69
5. Step 5: Solve for x
   x = 982,243.69/1,145.39
6. Step 6: Final answer
   x = 857.56