Finding the Fourth Proportional to 1,238.42, 1,709.01 and 678.89

Step by Step Solution

1. Step 1: Write the proportion equation
   1,238.42 : 1,709.01 = 678.89 : x
2. Step 2: Convert to fraction form
   1,238.42/1,709.01 = 678.89/x
3. Step 3: Cross multiply
   1,238.42x = 1,709.01 × 678.89
4. Step 4: Simplify right side
   1,238.42x = 1,160,221.25
5. Step 5: Solve for x
   x = 1,160,221.25/1,238.42
6. Step 6: Final answer
   x = 936.86