Finding the Fourth Proportional to 1,238.25, 1,708.77 and 678.72

Step by Step Solution

1. Step 1: Write the proportion equation
   1,238.25 : 1,708.77 = 678.72 : x
2. Step 2: Convert to fraction form
   1,238.25/1,708.77 = 678.72/x
3. Step 3: Cross multiply
   1,238.25x = 1,708.77 × 678.72
4. Step 4: Simplify right side
   1,238.25x = 1,159,776.37
5. Step 5: Solve for x
   x = 1,159,776.37/1,238.25
6. Step 6: Final answer
   x = 936.63