Finding the Fourth Proportional to 1,229.78, 1,695.20 and 980.71

Step by Step Solution

1. Step 1: Write the proportion equation
   1,229.78 : 1,695.20 = 980.71 : x
2. Step 2: Convert to fraction form
   1,229.78/1,695.20 = 980.71/x
3. Step 3: Cross multiply
   1,229.78x = 1,695.20 × 980.71
4. Step 4: Simplify right side
   1,229.78x = 1,662,490.45
5. Step 5: Solve for x
   x = 1,662,490.45/1,229.78
6. Step 6: Final answer
   x = 1,351.86