Finding the Fourth Proportional to 1,007.78, 1,390.38 and 658.67

Step by Step Solution

1. Step 1: Write the proportion equation
   1,007.78 : 1,390.38 = 658.67 : x
2. Step 2: Convert to fraction form
   1,007.78/1,390.38 = 658.67/x
3. Step 3: Cross multiply
   1,007.78x = 1,390.38 × 658.67
4. Step 4: Simplify right side
   1,007.78x = 915,801.59
5. Step 5: Solve for x
   x = 915,801.59/1,007.78
6. Step 6: Final answer
   x = 908.73