Finding the Fourth Proportional to 1,238.10, 1,708.59 and 678.55

Step by Step Solution

1. Step 1: Write the proportion equation
   1,238.10 : 1,708.59 = 678.55 : x
2. Step 2: Convert to fraction form
   1,238.10/1,708.59 = 678.55/x
3. Step 3: Cross multiply
   1,238.10x = 1,708.59 × 678.55
4. Step 4: Simplify right side
   1,238.10x = 1,159,363.56
5. Step 5: Solve for x
   x = 1,159,363.56/1,238.10
6. Step 6: Final answer
   x = 936.41