Finding the Fourth Proportional to 1,238.36, 1,708.83 and 678.81

Step by Step Solution

1. Step 1: Write the proportion equation
   1,238.36 : 1,708.83 = 678.81 : x
2. Step 2: Convert to fraction form
   1,238.36/1,708.83 = 678.81/x
3. Step 3: Cross multiply
   1,238.36x = 1,708.83 × 678.81
4. Step 4: Simplify right side
   1,238.36x = 1,159,977.30
5. Step 5: Solve for x
   x = 1,159,977.30/1,238.36
6. Step 6: Final answer
   x = 936.71