Finding the Fourth Proportional to 1,118.67, 1,543.78 and 621.30

Step by Step Solution

1. Step 1: Write the proportion equation
   1,118.67 : 1,543.78 = 621.30 : x
2. Step 2: Convert to fraction form
   1,118.67/1,543.78 = 621.30/x
3. Step 3: Cross multiply
   1,118.67x = 1,543.78 × 621.30
4. Step 4: Simplify right side
   1,118.67x = 959,150.51
5. Step 5: Solve for x
   x = 959,150.51/1,118.67
6. Step 6: Final answer
   x = 857.40