Finding the Fourth Proportional to 1,238.78, 1,858.20 and 554.78

Step by Step Solution

1. Step 1: Write the proportion equation
   1,238.78 : 1,858.20 = 554.78 : x
2. Step 2: Convert to fraction form
   1,238.78/1,858.20 = 554.78/x
3. Step 3: Cross multiply
   1,238.78x = 1,858.20 × 554.78
4. Step 4: Simplify right side
   1,238.78x = 1,030,892.20
5. Step 5: Solve for x
   x = 1,030,892.20/1,238.78
6. Step 6: Final answer
   x = 832.18