Finding the Fourth Proportional to 1,118.51, 1,543.55 and 621.15

Step by Step Solution

1. Step 1: Write the proportion equation
   1,118.51 : 1,543.55 = 621.15 : x
2. Step 2: Convert to fraction form
   1,118.51/1,543.55 = 621.15/x
3. Step 3: Cross multiply
   1,118.51x = 1,543.55 × 621.15
4. Step 4: Simplify right side
   1,118.51x = 958,772.98
5. Step 5: Solve for x
   x = 958,772.98/1,118.51
6. Step 6: Final answer
   x = 857.19