Finding the Fourth Proportional to 1,238.40, 1,858.12 and 892.72

Step by Step Solution

1. Step 1: Write the proportion equation
   1,238.40 : 1,858.12 = 892.72 : x
2. Step 2: Convert to fraction form
   1,238.40/1,858.12 = 892.72/x
3. Step 3: Cross multiply
   1,238.40x = 1,858.12 × 892.72
4. Step 4: Simplify right side
   1,238.40x = 1,658,780.89
5. Step 5: Solve for x
   x = 1,658,780.89/1,238.40
6. Step 6: Final answer
   x = 1,339.45