Finding the Fourth Proportional to 1,238.22, 1,708.74 and 678.72

Step by Step Solution

1. Step 1: Write the proportion equation
   1,238.22 : 1,708.74 = 678.72 : x
2. Step 2: Convert to fraction form
   1,238.22/1,708.74 = 678.72/x
3. Step 3: Cross multiply
   1,238.22x = 1,708.74 × 678.72
4. Step 4: Simplify right side
   1,238.22x = 1,159,756.01
5. Step 5: Solve for x
   x = 1,159,756.01/1,238.22
6. Step 6: Final answer
   x = 936.63