Finding the Fourth Proportional to 1,016.21, 1,403.05 and 623.91

Step by Step Solution

1. Step 1: Write the proportion equation
   1,016.21 : 1,403.05 = 623.91 : x
2. Step 2: Convert to fraction form
   1,016.21/1,403.05 = 623.91/x
3. Step 3: Cross multiply
   1,016.21x = 1,403.05 × 623.91
4. Step 4: Simplify right side
   1,016.21x = 875,375.37
5. Step 5: Solve for x
   x = 875,375.37/1,016.21
6. Step 6: Final answer
   x = 861.42