Finding the Fourth Proportional to 1,145.21, 1,580.35 and 621.23

Step by Step Solution

1. Step 1: Write the proportion equation
   1,145.21 : 1,580.35 = 621.23 : x
2. Step 2: Convert to fraction form
   1,145.21/1,580.35 = 621.23/x
3. Step 3: Cross multiply
   1,145.21x = 1,580.35 × 621.23
4. Step 4: Simplify right side
   1,145.21x = 981,760.83
5. Step 5: Solve for x
   x = 981,760.83/1,145.21
6. Step 6: Final answer
   x = 857.28