Finding the Fourth Proportional to 1,238.20, 1,856.87 and 458.03

Step by Step Solution

1. Step 1: Write the proportion equation
   1,238.20 : 1,856.87 = 458.03 : x
2. Step 2: Convert to fraction form
   1,238.20/1,856.87 = 458.03/x
3. Step 3: Cross multiply
   1,238.20x = 1,856.87 × 458.03
4. Step 4: Simplify right side
   1,238.20x = 850,499.88
5. Step 5: Solve for x
   x = 850,499.88/1,238.20
6. Step 6: Final answer
   x = 686.89