Finding the Fourth Proportional to 1,238.12, 1,856.69 and 458.00

Step by Step Solution

1. Step 1: Write the proportion equation
   1,238.12 : 1,856.69 = 458.00 : x
2. Step 2: Convert to fraction form
   1,238.12/1,856.69 = 458.00/x
3. Step 3: Cross multiply
   1,238.12x = 1,856.69 × 458.00
4. Step 4: Simplify right side
   1,238.12x = 850,355.88
5. Step 5: Solve for x
   x = 850,355.88/1,238.12
6. Step 6: Final answer
   x = 686.81