Finding the Fourth Proportional to 1,238.07, 1,708.56 and 678.56

Step by Step Solution

1. Step 1: Write the proportion equation
   1,238.07 : 1,708.56 = 678.56 : x
2. Step 2: Convert to fraction form
   1,238.07/1,708.56 = 678.56/x
3. Step 3: Cross multiply
   1,238.07x = 1,708.56 × 678.56
4. Step 4: Simplify right side
   1,238.07x = 1,159,360.47
5. Step 5: Solve for x
   x = 1,159,360.47/1,238.07
6. Step 6: Final answer
   x = 936.43