Finding the Fourth Proportional to 978.93, 1,470.15 and 939.78

Step by Step Solution

1. Step 1: Write the proportion equation
   978.93 : 1,470.15 = 939.78 : x
2. Step 2: Convert to fraction form
   978.93/1,470.15 = 939.78/x
3. Step 3: Cross multiply
   978.93x = 1,470.15 × 939.78
4. Step 4: Simplify right side
   978.93x = 1,381,617.57
5. Step 5: Solve for x
   x = 1,381,617.57/978.93
6. Step 6: Final answer
   x = 1,411.35