Finding the Fourth Proportional to 1,118.72, 1,543.78 and 621.32

Step by Step Solution

1. Step 1: Write the proportion equation
   1,118.72 : 1,543.78 = 621.32 : x
2. Step 2: Convert to fraction form
   1,118.72/1,543.78 = 621.32/x
3. Step 3: Cross multiply
   1,118.72x = 1,543.78 × 621.32
4. Step 4: Simplify right side
   1,118.72x = 959,181.39
5. Step 5: Solve for x
   x = 959,181.39/1,118.72
6. Step 6: Final answer
   x = 857.39