Finding the Fourth Proportional to 1,238.27, 1,708.80 and 678.76

Step by Step Solution

1. Step 1: Write the proportion equation
   1,238.27 : 1,708.80 = 678.76 : x
2. Step 2: Convert to fraction form
   1,238.27/1,708.80 = 678.76/x
3. Step 3: Cross multiply
   1,238.27x = 1,708.80 × 678.76
4. Step 4: Simplify right side
   1,238.27x = 1,159,865.50
5. Step 5: Solve for x
   x = 1,159,865.50/1,238.27
6. Step 6: Final answer
   x = 936.69